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[CLJ-1933] please add unless macro for symmetry with when Created: 27/May/16  Updated: 27/May/16  Resolved: 27/May/16

Status: Closed
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Enhancement Priority: Trivial
Reporter: Ernesto Alfonso Assignee: Unassigned
Resolution: Declined Votes: 0
Labels: enhancement


Is there a reason there is a `when` macro but no `unless`? I think it useful, CL uses it, adds consistency/symmetry and conciseness to code.

(defmacro unless [test & body]
`(when (not ~test) ~@body))

Comment by Ragnar Dahlen [ 27/May/16 2:28 PM ]

There is already when-not: http://clojure.github.io/clojure/clojure.core-api.html#clojure.core/when-not

Comment by Alex Miller [ 27/May/16 3:47 PM ]

As Ragnar says, when-not is equivalent.

[CLJ-1934] (s/cat) with nonconforming data causes infinite loop in explain-data Created: 27/May/16  Updated: 27/May/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.9
Fix Version/s: Release 1.9

Type: Defect Priority: Major
Reporter: Sven Richter Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: spec

Ubuntu 15.10
Leiningen 2.6.1 on Java 1.8.0_91 Java HotSpot(TM) 64-Bit Server VM

Attachments: Text File clj-1934.patch    
Patch: Code and Test
Approval: Vetted


The following code yields an infinite loop

(require '[clojure.spec :as s])
(s/explain-data (s/cat) [1]) ;; infinite loop

Thread dump:

"main" prio=5 tid=0x00007fb602000800 nid=0x1703 runnable [0x0000000102b3f000]
   java.lang.Thread.State: RUNNABLE
	at clojure.lang.RT.seqFrom(RT.java:529)
	at clojure.lang.RT.seq(RT.java:524)
	at clojure.core$seq__5444.invokeStatic(core.clj:137)
	at clojure.core$concat$cat__5535$fn__5536.invoke(core.clj:715)
	at clojure.lang.LazySeq.sval(LazySeq.java:40)
	- locked <0x000000015885e4e0> (a clojure.lang.LazySeq)
	at clojure.lang.LazySeq.seq(LazySeq.java:56)
	- locked <0x000000015885e2f0> (a clojure.lang.LazySeq)
	at clojure.lang.RT.seq(RT.java:522)
	at clojure.core$seq__5444.invokeStatic(core.clj:137)
	at clojure.core$map$fn__5872.invoke(core.clj:2637)
	at clojure.lang.LazySeq.sval(LazySeq.java:40)
	- locked <0x000000015885e3b0> (a clojure.lang.LazySeq)
	at clojure.lang.LazySeq.seq(LazySeq.java:49)
	- locked <0x000000015885e3b0> (a clojure.lang.LazySeq)
	at clojure.lang.ChunkedCons.chunkedNext(ChunkedCons.java:59)
	at clojure.lang.ChunkedCons.next(ChunkedCons.java:43)
	at clojure.lang.RT.next(RT.java:689)
	at clojure.core$next__5428.invokeStatic(core.clj:64)
	at clojure.core$dorun.invokeStatic(core.clj:3033)
	at clojure.core$doall.invokeStatic(core.clj:3039)
	at clojure.walk$walk.invokeStatic(walk.clj:46)
	at clojure.walk$postwalk.invokeStatic(walk.clj:52)
	at clojure.spec$abbrev.invokeStatic(spec.clj:114)
	at clojure.spec$re_explain.invokeStatic(spec.clj:1286)
	at clojure.spec$regex_spec_impl$reify__11725.explain_STAR_(spec.clj:1305)
	at clojure.spec$explain_data_STAR_.invokeStatic(spec.clj:143)
	at clojure.spec$spec_checking_fn$conform_BANG___11409.invoke(spec.clj:528)
	at clojure.spec$spec_checking_fn$fn__11414.doInvoke(spec.clj:540)
	at clojure.lang.RestFn.invoke(RestFn.java:408)
	at user$eval8.invokeStatic(NO_SOURCE_FILE:5)
	at user$eval8.invoke(NO_SOURCE_FILE:5)
	at clojure.lang.Compiler.eval(Compiler.java:6942)
	at clojure.lang.Compiler.eval(Compiler.java:6905)
	at clojure.core$eval.invokeStatic(core.clj:3105)
	at clojure.core$eval.invoke(core.clj:3101)
	at clojure.main$repl$read_eval_print__8495$fn__8498.invoke(main.clj:240)
	at clojure.main$repl$read_eval_print__8495.invoke(main.clj:240)
	at clojure.main$repl$fn__8504.invoke(main.clj:258)
	at clojure.main$repl.invokeStatic(main.clj:258)
	at clojure.main$repl_opt.invokeStatic(main.clj:322)
	at clojure.main$main.invokeStatic(main.clj:421)
	at clojure.main$main.doInvoke(main.clj:384)
	at clojure.lang.RestFn.invoke(RestFn.java:397)
	at clojure.lang.Var.invoke(Var.java:375)
	at clojure.lang.AFn.applyToHelper(AFn.java:152)
	at clojure.lang.Var.applyTo(Var.java:700)
	at clojure.main.main(main.java:37)

Cause: This line in op-describe:

(cons `cat (mapcat vector (c/or (seq ks) (repeat :_)) (c/or (seq forms) (repeat nil)))))

is called here with no ks or form, so will mapcat vector over infinite streams of :_ and nil.

Approach: check for this case and avoid doing that

Patch: clj-1934.patch

[CLJ-946] eval reader fail to recognize function object Created: 06/Mar/12  Updated: 27/May/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.3
Fix Version/s: None

Type: Defect Priority: Minor
Reporter: Naitong Xiao Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: reader

(defmacro stubbing [stub-forms & body]
  (let [stub-pairs (partition 2 stub-forms)
        returns (map last stub-pairs)
        stub-fns (map constantly returns)  ;;(map #(list 'constantly %) returns)
        real-fns (map first stub-pairs)]
    `(binding [~@(interleave real-fns stub-fns)]

This macro is from Clojure In Action , whith the commented line rewrited (I know that original is better)
I assumed that this macro would work as supposed , if the stub forms use compile time literal, for e.g

(def ^:dynamic $ (fn [x] (* x 10))

(stubbing [$ 1]
        ($ 1 1))
;; =>
IllegalArgumentException No matching ctor found for class clojure.core$constantly$fn__3656
	clojure.lang.Reflector.invokeConstructor (Reflector.java:166)
	clojure.lang.LispReader$EvalReader.invoke (LispReader.java:1031)
	clojure.lang.LispReader$DispatchReader.invoke (LispReader.java:618)

;;macro can expanded  
(macroexpand-all '(stubbing [$ 1]
                ($ 1 1)))
;; =>
(let* [] (clojure.core/push-thread-bindings (clojure.core/hash-map (var $) #<core$constantly$fn__3656 clojure.core$constantly$fn__3656@161f888>)) (try ($ 1 1) (finally (clojure.core/pop-thread-bindings))))

I thought there is something wrong with eval reader, but i can't figure it out

btw the above code can run on clojure-clr

Comment by Michael Klishin [ 06/Mar/12 11:24 PM ]

As far as I know, Clojure in Action examples are written for Clojure 1.2. What version are you using?

Comment by Naitong Xiao [ 07/Mar/12 1:24 AM ]

I use clojure 1.3

The example in Clojure In Action is Ok on clojure 1.3
I just found this peculiar thing when trying to answer a question from another one in a mail list.

Comment by Greg Chapman [ 23/May/16 7:52 PM ]

FWIW, This still happens with Clojure 1.8. I believe what happens, is, when given a value of type Fn (like that produced by a call to constantly), the compiler's emitValue method will call RT.printString. This will result in a call to print-dup on the value, producing a string like this:

#=(clojure.core$constantly$fn__4614. )

So the LispReader will try to evaluate a call to a 0-argument constructor for the Fn object. This will not work for a closure (such as that produced by constantly), since the closure needs the values closed-over to be supplied to its constructor (so there is no matching ctor).

This could probably have some better error message; I ran into it today and it took me awhile to understand why the EvalReader was even coming into play.

Comment by Steve Miner [ 25/May/16 3:00 PM ]

Sounds like a duplicate of CLJ-1206 which was recently declined. There are some potential work-arounds in that bug.

Comment by Greg Chapman [ 27/May/16 11:20 AM ]

It appears CLJ-1928 has been opened to improve the error message. So this issue should probably be closed.

[CLJ-1932] Add clojure.spec/explain-str to return explain output as a string Created: 25/May/16  Updated: 26/May/16  Resolved: 26/May/16

Status: Closed
Project: Clojure
Component/s: None
Affects Version/s: Release 1.9
Fix Version/s: Release 1.9

Type: Enhancement Priority: Major
Reporter: D. Theisen Assignee: Unassigned
Resolution: Completed Votes: 0
Labels: spec

Approval: Vetted


Currently explain prints to *out* - add a function explain-str that returns the explain output as a string.

Comment by Alex Miller [ 25/May/16 9:51 AM ]

You can easily capture the string with (with-out-str (s/explain spec data)).

Comment by Alex Miller [ 26/May/16 8:35 AM ]

explain-str was added in https://github.com/clojure/clojure/commit/575b0216fc016b481e49549b747de5988f9b455c for 1.9.0-alpha3.

[CLJ-1903] Provide a transducer for reductions Created: 17/Mar/16  Updated: 25/May/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Enhancement Priority: Major
Reporter: Pierre-Yves Ritschard Assignee: Unassigned
Resolution: Unresolved Votes: 1
Labels: transducers

Attachments: Text File 0001-clojure.core-add-reductions-stateful-transducer.patch     Text File 0002-clojure.core-add-reductions-with-for-init-passing-va.patch    
Patch: Code and Test
Approval: Triaged


Reductions does not currently provide a transducer when called with a 1-arity.


  • A reductions transducer
  • Similar to seequence reductions, initial state is not included in reductions
(assert (= (sequence (reductions +) nil) []))
(assert (= (sequence (reductions +) [1 2 3 4 5]) [1 3 6 10 15]))

A second patch proposes a variant which allows explicit initialization values: reductions-with

(assert (= (sequence (reductions-with + 0) [1 2 3 4 5]) [1 3 6 10 15])))

Patch: 0001-clojure.core-add-reductions-stateful-transducer.patch
Patch: 0002-clojure.core-add-reductions-with-for-init-passing-va.patch

Comment by Steve Miner [ 17/Mar/16 3:47 PM ]

The suggested patch gets the "init" value for the reductions by calling the function with no args. I would like a "reductions" transducer that took an explicit "init" rather than relying on a nullary (f).

If I remember correctly, Rich has expressed some regrets about supporting reduce without an init (ala Common Lisp). My understanding is that an explicit init is preferred for new Clojure code.

Unfortunately, an explicit init arg for the transducer would conflict with the standard "no-init" reductions [f coll]. In my own code, I've used the name "accumulations" for this transducer. Another possible name might be "reductions-with".

Comment by Pierre-Yves Ritschard [ 17/Mar/16 4:38 PM ]

Hi Steve,

I'd much prefer for init values to be explicit as well, unfortunately, short of testing the 2nd argument in the 2-arity variant - which would probably be even more confusing, there's no way to do that with plain "reductions".

I like the idea of providing a "reductions-with" variant that forced the init value and I'm happy to augment the patch with that if needed.

Comment by Pierre-Yves Ritschard [ 18/Mar/16 3:35 AM ]

@Steve Miner I added a variant with reductions-with.

Comment by Pierre-Yves Ritschard [ 24/May/16 6:40 AM ]

Is there anything I can help to move this forward?
@alexmiller any comments on the code itself?

Comment by Alex Miller [ 24/May/16 7:31 AM ]

Haven't had a chance to look at it yet, sorry.

Comment by Pierre-Yves Ritschard [ 24/May/16 7:36 AM ]

@alexmiller, if the upshot is getting clojure.spec, I'll take this taking a bit of time to review

Comment by Steve Miner [ 25/May/16 3:21 PM ]

For testing, I suggest you compare the output from the transducer version to the output from a simliar call to the sequence reductions. For example,

(is (= (reductions + 3 (range 20)) (sequence (reductions-with + 3) (range 20)))

I would like to see that equality hold. The 0002 patch doesn't handle the init the same way the current Clojure reductions does.

[CLJ-1931] clojure.spec/with-gen throws AbstractMethodError Created: 24/May/16  Updated: 25/May/16  Resolved: 25/May/16

Status: Closed
Project: Clojure
Component/s: None
Affects Version/s: Release 1.9
Fix Version/s: None

Type: Defect Priority: Major
Reporter: Tyler van Hensbergen Assignee: Unassigned
Resolution: Completed Votes: 0
Labels: None

OSX Yosemite 10.10.5


An AbstractMethodError is encountered when trying to evaluate a s/def form with the generator-fn overridden using s/with-gen.

(ns spec-fun.core
  (:require [clojure.spec :as s]
            [clojure.test.check.generators :as gen]))

(s/def ::int integer?)

(s/def ::int-vec
    (s/& (s/cat :first ::int
                :rest  (s/* integer?)
                :last  ::int)
         #(= (:first %) (:last %)))
    #(gen/let [first (s/gen integer?)
               rest  (gen/such-that
                      (partial at-least 3)
                      (gen/vector (s/gen integer?)))]
       (concat [first] rest [first]))))
;;=> AbstractMethodError

;; The generator works independently
(gen/generate (gen/let [first (s/gen integer?)
                        rest  (gen/such-that
                               (partial at-least 3)
                               (gen/vector (s/gen integer?)))]
                (concat [first] rest [first])))
;;=> (-13 8593 -33421108 4 6697 0 35835865 -94366552 1 14165115 -4090 42 775 -15238320 233500020 -1 -13)

;; And so does the spec:
(s/def ::int-vec
  (s/& (s/cat :first ::int
              :rest  (s/* integer?)
              :last  ::int)
       #(= (:first %) (:last %))))

(s/conform ::int-vec '(-13 8593 -33421108 4 6697 0 35835865 -94366552 1 14165115 -4090 42 775 -15238320 233500020 -1 -13))
;;=> {:first -13, :rest [8593 -33421108 4 6697 0 35835865 -94366552 1 14165115 -4090 42 775 -15238320 233500020 -1], :last -13}

Comment by Alex Miller [ 25/May/16 10:13 AM ]

Fixed in commit https://github.com/clojure/clojure/commit/ec2512edad9c0c4a006980eedd2a6ee8679d4b5d for 1.9 alpha2.

[CLJ-1623] Support zero-depth structures for update and update-in Created: 22/Dec/14  Updated: 23/May/16  Resolved: 22/May/16

Status: Closed
Project: Clojure
Component/s: None
Affects Version/s: Release 1.7
Fix Version/s: None

Type: Enhancement Priority: Minor
Reporter: Mike Anderson Assignee: Unassigned
Resolution: Declined Votes: 1
Labels: None


Currently "update" and "update-in" assume a nested associative structure at least 1 level deep.

For greater generality, it would be preferable to also support the case of 0 levels deep (i.e. a nested associative structure where there is only a leaf node)


;; Zero-length paths would be supported in update-in
(update-in 1 [] inc) => 2

;; update would get an extra arity which simply substitutes the new value
(update :old :new) => :new

Comment by Ghadi Shayban [ 23/Dec/14 7:56 AM ]

Duplicate of CLJ-373 which has been declined?

Comment by Alex Miller [ 23/Dec/14 8:19 AM ]

Rich has declined similar requests in the past.

Comment by Mike Anderson [ 23/Dec/14 7:50 PM ]

I disagree with the reasons for rejecting the previous patch. Can we revisit this?

Yes, it is a (very minor) behaviour change for update-in, but only only on undefined implementation behaviour, and even then only on the error case. If people are relying on this then their code is already very broken.

On the plus side, is makes the behaviour more logical and consistent. There is clearly demand for the change (see the various comments in favour of improving this in CLJ-373)

As an aside: if you really want to keep the old behaviour of disallowing empty paths then it would be better to convert the NullPointerException into a meaningful error message e.g. "Empty key paths are not allowed"

Also, I am proposing a corresponding change to update which doesn't have the above concern (since it is introducing a whole new arity)

Comment by Alex Miller [ 24/Dec/14 7:55 AM ]

Sorry, Rich has said he's not interested.

Comment by Herwig Hochleitner [ 22/May/16 8:39 PM ]

Please ask Rich to consider the pattern

(update-in {} (compute-path ..) assoc ...)

this would be perfectly fine, if not for the currently buggy behavior.

Comment by Alex Miller [ 22/May/16 10:20 PM ]

This was considered and the decision was that update and update-in require a path with length > 1.

Comment by Mike Anderson [ 22/May/16 10:27 PM ]

@Alex - Can you provide a rationale for this decision for future reference?

Comment by Alex Miller [ 23/May/16 5:58 AM ]

update and update-in are about updating nested paths and a "path" implies at least one segment.

Comment by Alex Miller [ 23/May/16 6:14 AM ]

Sorry that should have been path with length >= 1 above! Grr.

[CLJ-1930] IntelliJ doesn't allow debugging of clojure varargs from Java Created: 22/May/16  Updated: 22/May/16  Resolved: 22/May/16

Status: Closed
Project: Clojure
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Defect Priority: Critical
Reporter: Mathias Bogaert Assignee: Unassigned
Resolution: Declined Votes: 0
Labels: None

Attachments: PNG File intellij.png    


When trying to debug evaluate Datomic's datoms API IntelliJ or the method thows "java.lang.IllegalArgumentException : Invalid argument count: expected 2, received 3". Debugging Java varargs is not an issue.

Using IntelliJ 2016.2 CE.

Comment by Mathias Bogaert [ 22/May/16 9:06 AM ]

Datomic 0.9.5359, JDK 1.8.0_74, OS/X 10.11.5.

Comment by Kevin Downey [ 22/May/16 1:56 PM ]

hi, this is the issue tracker for the Clojure programming language, not Datomic or Intellij. http://www.datomic.com/support.html lists various support options for datomic

Comment by Alex Miller [ 22/May/16 3:55 PM ]

Agreed with Kevin, this is an issue with Cursive and you can find that tracker here:


I think this existing ticket is relevant:


[CLJ-1910] Namespaced maps Created: 07/Apr/16  Updated: 22/May/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: None
Fix Version/s: Release 1.9

Type: Enhancement Priority: Critical
Reporter: Alex Miller Assignee: Alex Miller
Resolution: Unresolved Votes: 0
Labels: print, reader

Attachments: Text File clj-1910-2.patch     Text File clj-1910.patch    
Patch: Code and Test
Approval: Ok


A common usage of namespaced keywords and symbols is in providing attribute disambiguation in map contexts:

{:person/first "Han" :person/last "Solo" :person/ship 
  {:ship/name "Millenium Falcon" :ship/model "YT-1300f light freighter"}}

The namespaces provide value (disambiguation) but have the downside of being repetitive and verbose.

Namespaced maps are a reader (and printer) feature to specify a namespace context for a map.

  • Namespaced maps combine a default namespace with a map and yield a map.
  • Namespaced maps are reader macros starting with #: or #::, followed by a normal map definition.
    • #:sym indicates that sym is the default namespace for the map to follow.
    • #:: indicates that the default namespace auto-resolves to the current namespace.
    • #::sym indicates that sym should be auto-resolved using the current namespace's aliases OR any fully-qualified loaded namespace.
      • These rules match the rules for auto-resolved keywords.
  • A namespaced map is read with the following differences from normal maps:
    • A keyword or symbol key without a namespace is read with the default namespace as its namespace.
    • Keys that are not symbols or keywords are not affected.
    • Keys that specify an explicit namespace are not affected EXCEPT the special namespace _, which is read with NO namespace. This allows the specification of bare keys in a namespaced map.
    • Values are not affected.
    • Nested map keys are not affected.
  • The edn reader supports #: but not #:: with the same rules as above.
  • Maps will be printed in namespaced map form only when:
    • All map keys are keywords or symbols
    • All map keys are namespaced
    • All map keys have the same namespace


;; same as above - notice you can nest #: maps and this is a case where the printer roundtrips
user=> #:person{:first "Han" :last "Solo" :ship #:ship{:name "Millenium Falcon" :model "YT-1300f light freighter"}}
#:person{:first "Han" :last "Solo" :ship #:ship{:name "Millenium Falcon" :model "YT-1300f light freighter"}}

;; effects on keywords with ns, without ns, with _ ns, and non-kw
user=> #:foo{:kw 1, :n/kw 2, :_/bare 3, 0 4}
{:foo/kw 1, :n/kw 2, :bare 3, 0 4}

;; auto-resolved namespaces (will use user as the ns)
user=> #::{:kw 1, :n/kw 2, :_/bare 3, 0 4}
:user/kw 1, :n/kw 2, :bare 3, 0 4}

;; auto-resolve alias s to clojure.string
user=> (require '[clojure.string :as s])
user=> #::s{:kw 1, :n/kw 2, :_/bare 3, 0 4}
{:clojure.string/kw 1, :n/kw 2, :bare 3, 0 4}

;; to show symbol changes, we'll quote the whole thing to avoid evaluation
user=> '#::{a 1, n/b 2, _/c 3}
{user/a 1, n/b 2, c 3}

;; edn reader also supports (only) the #: syntax
user=> (clojure.edn/read-string "#:person{:first \"Han\" :last \"Solo\" :ship #:ship{:name \"Millenium Falcon\" :model \"YT-1300f light freighter\"}}")
#:person{:first "Han", :last "Solo", :ship #:ship{:name "Millenium Falcon", :model "YT-1300f light freighter"}}

Patch: clj-1910-2.patch

Screener notes:

  • Autoresolution supports fully-qualified loaded namespaces (like auto-resolved keywords)
  • TODO: pprint support for namespaced maps
  • TODO: printer flag to suppress printing namespaced maps

Comment by Nicola Mometto [ 08/Apr/16 3:57 AM ]

1- yes please. that's consistent with how tagged literals work.
2- no please. that would make the proposed syntax useless for e.g. Datomic schemas, for which I think this would be a good fit to reduce noise
3- yes please
4- yes please, consistency over print methods is important

Comment by Nicola Mometto [ 08/Apr/16 4:00 AM ]

Quoting from a post I wrote on the clojure-dev ML:

  • I really don't like the idea of special-casing `_` here, users are already confused about idioms like `[.. & _]` thinking that `_` is some special token/variable. Making it an actual special token in some occasion wouldn't help.
  • I also don't like how we're making the single `:` auto-qualify keywords when used within the context of a qualifying-map. Auto-qualifying keywords has always been the job of the double `::`, changing this would introduce (IMO) needless cognitive overhead.
  • The current impl treats `#:foo{'bar 1}` and `'#:foo{bar 1}` differently. I can see why is that, but the difference might be highly unintuitive to some.
  • The current proposal makes it feel like quote is auto-qualifying symbols , when that has always been the job of syntax-quote. I know that's not correct, but that's how it's perceived.

Here's an alternative syntax proposal that handles all those issues:

  • No #::, only #:foo or #::foo
  • No auto-resolution of symbols when the namespaced-map is quoted, only when syntax-quoted
  • No special-casing of `_`
  • No auto-resolution of single-colon keywords

Here's how the examples in the ticket description would look:

#:person{::first "Han", ::last "Solo", ::ship #:ship{::name "Millenium Falcon", ::model "YT-1300f light freighter"}}
;=> {:person/first "Han" :person/last "Solo" :person/ship {:ship/name "Millenium Falcon" :ship/model "YT-1300f light freighter"}}

#:foo{::kw 1, :n/kw 2, :bare 3, 0 4}
;=> {:foo/kw 1, :n/kw 2, :bare 3, 0 4}

{::kw 1, :n/kw 2, bare 3, 0 4}
;=> {:user/kw 1, :n/kw 2, :bare 3, 0 4}

Note in the previous example how we don't need `#::` at all – `::` already does that job for us

(require '[clojure.string :as s])
#::s{::kw 1, :n/kw 2, bare 3, 0 4}
;=> {:clojure.string/kw 1, :n/kw 2, :bare 3, 0 4}

`{a 1, n/b 2, ~'c 3}
;=> {user/a 1, n/b 2, c 3}

Again, no need for `#::` here, we can just rely on the existing auto-qualifying behaviour of `.

`#:foo{a 1, n/b 2}
;=> {foo/a 1, n/b 2}

I think this would be more consistent with the existing behaviour – it's basically just making `#:foo` or `#::foo` mean: in the top-level keys of the following map expression, resolve keywords/symbols as if ns was bound to `foo`, rather than introducing new resolution rules and special tokens.

I realize that this proposal wouldn't work with EDNReader as-is, given its lack of support for `::` and "`". I don't have a solution to that other than "let's just bite the bullet and implement them there too", but maybe that's not acceptable.

Comment by Alex Miller [ 08/Apr/16 8:45 AM ]

Nicola, thanks for the proposal, we talked through it. We share your dislike for :_/kw syntax and you should consider that a placeholder for this behavior for the moment - it may be removed or replaced before we get to a published release.

For the rest of it:

  • requiring syntax quote is a non-starter
  • supporting a mixture of default ns and the current ns is important and this is not possible with your proposal. Like #:foo{:bar 1 ::baz 2}.
  • there is a lot of value to changing the scope of a map without modifying the contents, which is an advantage of the syntax in the ticket
Comment by Christophe Grand [ 08/Apr/16 10:31 AM ]

Why restrict this feature to a single namespace? (this doesn't preclude a shorthand for the single mapping) I'd like to locally define aliases (and default ns).

Comment by Alex Miller [ 08/Apr/16 11:02 AM ]

We already have namespace level aliases. You can use :: in the map to leverage those aliases (independently from the default ns):

(ns app 
  (:require [my.domain :as d]
            [your.domain :as y]))

#::{:svc 1, ::d/name 2, ::y/name 3}

;;=> {:app/svc 1, :my.domain/name 2, :your.domain/y 3}
Comment by Christophe Grand [ 11/Apr/16 4:03 AM ]

Alex, if existing namespace level aliases are enough when there's more than one namespace used in the key set I fail to understand the real value of this proposal.

Okay I'm lying a little: there are no aliases in edn, so this would bring aliases to edn (and allows printers to factor/alias namespaces out). And for Clojure code you can't define an alias to a non-existing namespace – and I believe that this implementation wouldn't check namespace existence when resolving the default ns #:person{:name}.

Still my points hold for edn (and that's where the value of this proposal seems to be): why not allows local aliases too?

#:person #:employee/e {:name "John Smith", :e/eid "012345"}
;=> {:person/name "John Smith", :employee/eid "012345"}

I have another couple of questions:

  • should it apply to other datatypes?
  • should it be transitive?
Comment by Alex Miller [ 28/Apr/16 1:33 PM ]

New patch rev supports spaces between the namespace part #:foo and the map in both LispReader and EdnReader.

[CLJ-1919] Destructuring support for namespaced keys and syms Created: 27/Apr/16  Updated: 20/May/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: None
Fix Version/s: Release 1.9

Type: Enhancement Priority: Critical
Reporter: Alex Miller Assignee: Alex Miller
Resolution: Unresolved Votes: 0
Labels: destructuring

Attachments: Text File clj-1919.patch    
Patch: Code and Test
Approval: Ok


Expand destructuring to better support a set of keys (or syms) from a map when the keys share the same namespace.


(def m {:person/first "Darth" :person/last "Vader" :person/email "darth@death.star"})

(let [{:keys [person/first person/last person/email]} m]
  (format "%s %s - %s" first last email))

Proposed: The special :keys and :syms keywords used in associative destructuring may now have a namespace (eg :person/keys). That namespace will be applied during lookup to all listed keys or syms when they are retrieved from the input map.

Example (also uses the new literal syntax for namespaced maps from CLJ-1910):

(def m #:person{:first "Darth" :last "Vader" :email "darth@death.star"})

(let [{:person/keys [first last email]} m]
  (format "%s %s - %s" first last email))
  • The key list after :ns/keys should contain either non-namespaced symbols or non-namespaced keywords. Symbols are preferred.
  • The key list after :ns/syms should contain non-namespaced symbols.
  • As :ns/keys and :ns/syms are read as normal keywords, auto-resolved keywords work as well: ::keys, ::alias/keys, etc.
  • Clarification - the :or defaults map always uses non-namespaced symbols as keys - that is, they are always the same as the locals being created (not the keys being looked up in the map). No change in behavior here, just trying to be explicit - this was not previously well-documented for namespaced key lookup and was broken. The attached patch fixes this behavior.

Patch: clj-1919.patch

[CLJ-1517] Unrolled small vectors Created: 01/Sep/14  Updated: 18/May/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.7
Fix Version/s: Backlog

Type: Enhancement Priority: Critical
Reporter: Zach Tellman Assignee: Unassigned
Resolution: Unresolved Votes: 22
Labels: collections, performance

Attachments: File unrolled-collections-2.diff     File unrolled-collections.diff     Text File unrolled-vector-2.patch     Text File unrolled-vector.patch    
Patch: Code
Approval: Incomplete


As discussed on the mailing list [1], this patch has two unrolled variants of vectors and maps, with special inner classes for each cardinality. Currently both grow to six elements before spilling over into the general versions of the data structures, which is based on rough testing but can be easily changed. At Rich's request, I haven't included any integration into the rest of the code, and there are top-level static create() methods for each.

The sole reason for this patch is performance, both in terms of creating data structures and performing operations on them. This can be seen as a more verbose version of the trick currently played with PersistentArrayMap spilling over into PersistentHashMap. Based on the benchmarks, which can be run by cloning cambrian-collections [2] and running 'lein test :benchmark', this should supplant PersistentArrayMap. Performance is at least on par with PAM, and often much faster. Especially noteworthy is the creation time, which is 5x faster for maps of all sizes (lein test :only cambrian-collections.map-test/benchmark-construction), and on par for 3-vectors, but 20x faster for 5-vectors. There are similar benefits for hash and equality calculations, as well as calls to reduce().

This is a big patch (over 5k lines), and will be kind of a pain to review. My assumption of correctness is based on the use of collection-check, and the fact that the underlying approach is very simple. I'm happy to provide a high-level description of the approach taken, though, if that will help the review process.

I'm hoping to get this into 1.7, so please let me know if there's anything I can do to help accomplish that.

[1] https://groups.google.com/forum/#!topic/clojure-dev/pDhYoELjrcs
[2] https://github.com/ztellman/cambrian-collections

Patch: unrolled-vector-2.patch

Screener Notes: The approach is clear and understandable. Given the volume of generated code, I believe that best way to improve confidence in this code is to get people using it asap, and add collection-test [3] to the Clojure test suite. I would also like to get the generator [4] included in the Clojure repo. We don't need to necessarily automate running it, but would be nice to have it nearby if we want to tweak something later.

[3] https://github.com/ztellman/collection-check/blob/master/src/collection_check.clj
[4] https://github.com/ztellman/cambrian-collections/blob/master/generate/cambrian_collections/vector.clj

Comment by Zach Tellman [ 01/Sep/14 10:13 PM ]

Oh, I forgot to mention that I didn't make a PersistentUnrolledSet, since the existing wrappers can use the unrolled map implementation. However, it would be moderately faster and more memory efficient to have one, so let me know if it seems worthwhile.

Comment by Nicola Mometto [ 02/Sep/14 5:23 AM ]

Zach, the patch you added isn't in the correct format, they need to be created using `git format-patch`

Comment by Nicola Mometto [ 02/Sep/14 5:31 AM ]

Also, I'm not sure if this is on-scope with the ticket but those patches break with *print-dup*, as it expects a static create(x) method for each inner class.

I'd suggest adding a create(Map x) static method for the inner PersistentUnrolledMap classes and a create(ISeq x) one for the inner PersistentUnrolledVector classes

Comment by Alex Miller [ 02/Sep/14 8:14 AM ]

Re making patches, see: http://dev.clojure.org/display/community/Developing+Patches

Comment by Jozef Wagner [ 02/Sep/14 9:16 AM ]

I wonder what is the overhead of having meta and 2 hash fields in the class. Have you considered a version where the hash is computed on the fly and where you have two sets of collections, one with meta field and one without, using former when the actual metadata is attached to the collection?

Comment by Zach Tellman [ 02/Sep/14 12:13 PM ]

I've attached a patch using the proper method. Somehow I missed the detailed explanation for how to do this, sorry. I know the guidelines say not to delete previous patches, but since the first one isn't useful I've deleted it to minimize confusion.

I did the print-dup friendly create methods, and then realized that once these are properly integrated, 'pr' will just emit these as vectors. I'm fairly sure the create methods aren't necessary, so I've commented them out, but I'm happy to add them back in if they're useful for some reason I can't see.

I haven't given a lot of thought to memory efficiency, but I think caching the hashes are worthwhile. I can see an argument for creating a "with-meta" version of each collection, but since that would double the size of an already enormous patch, I think that should probably wait.

Comment by Zach Tellman [ 03/Sep/14 4:31 PM ]

I found a bug! Like PersistentArrayMap, I have a special code path for comparing keywords, but my generators for collection-check were previously using only integer keys. There was an off-by-one error in the transient map implementation [1], which was not present for non-keyword lookups.

I've taken a close look for other gaps in my test coverage, and can't find any. I don't think this substantively changes the risk of this patch (an updated version of which has been uploaded as 'unrolled-collections-2.diff'), but obviously where there's one bug, there may be others.

[1] https://github.com/ztellman/cambrian-collections/commit/eb7dfe6d12e6774512dbab22a148202052442c6d#diff-4bf78dbf5b453f84ed59795a3bffe5fcR559

Comment by Zach Tellman [ 03/Oct/14 2:34 PM ]

As an additional data point, I swapped out the data structures in the Cheshire JSON library. On the "no keyword-fn decode" benchmark, the current implementation takes 6us, with the unrolled data structures takes 4us, and with no data structures (just lexing the JSON via Jackson) takes 2us. Other benchmarks had similar results. So at least in this scenario, it halves the overhead.

Benchmarks can be run by cloning https://github.com/dakrone/cheshire, unrolled collections can be tested by using the 'unrolled-collections' branch. The pure lexing benchmark can be reproduced by messing around with the cheshire.parse namespace a bit.

Comment by Zach Tellman [ 06/Oct/14 1:31 PM ]

Is there no way to get this into 1.7? It's an awfully big win to push off for another year.

Comment by Alex Miller [ 07/Oct/14 2:08 PM ]

Hey Zach, it's definitely considered important but we have decided to drop almost everything not fully done for 1.7. Timeframe for following release is unknown, but certainly expected to be significantly less than a year.

Comment by John Szakmeister [ 30/Oct/14 2:53 PM ]

You are all free to determine the time table, but I thought I'd point out that Zach is not entirely off-base. Clojure 1.4.0 was released April 5th, 2012. Clojure 1.5.0 was released March 1st, 2013 with 1.6.0 showing up March 25th, 2014. So it appears that the current cadence is around a year.

Comment by Alex Miller [ 30/Oct/14 3:40 PM ]

John, there is no point to comments like this. Let's please keep issue comments focused on the issue.

Comment by Zach Tellman [ 13/Nov/14 12:23 PM ]

I did a small write-up on this patch which should help in the eventual code review: http://blog.factual.com/using-clojure-to-generate-java-to-reimplement-clojure

Comment by Zach Tellman [ 07/Dec/14 10:34 PM ]

Per my conversation with Alex at the Conj, here's a patch that only contains the unrolled vectors, and uses the more efficient constructor for PersistentVector when spilling over.

Comment by Alex Miller [ 08/Dec/14 1:10 PM ]

Zach, I created a new placeholder for the map work at http://dev.clojure.org/jira/browse/CLJ-1610.

Comment by Jean Niklas L'orange [ 09/Dec/14 1:52 PM ]

It should probably be noted that core.rrb-vector will break for small vectors by this patch, as it peeks into the underlying structure. This will also break other libraries which peeks into the vector implementation internals, although I'm not aware of any other – certainly not any other contrib library.

Also, two comments on unrolled-vector.patch:

private transient boolean edit = true;
in the Transient class should probably be
private volatile boolean edit = true;
as transient means something entirely different in Java.

conj in the Transient implementation could invalidate itself without any problems (edit = false;) if it is converted into a TransientVector (i.e. spills over) – unless it has a notable overhead. The invalidation can prevent some subtle bugs related to erroneous transient usage.

Comment by Alex Miller [ 09/Dec/14 1:58 PM ]

Jean - understanding the scope of the impact will certainly be part of the integration process for this patch. I appreciate the heads-up. While we try to minimize breakage for things like this, it may be unavoidable for libraries that rely on implementation internals.

Comment by Michał Marczyk [ 09/Dec/14 2:03 PM ]

I'll add support for unrolled vectors to core.rrb-vector the moment they land on master. (Probably with some conditional compilation so as not to break compatibility with earlier versions of Clojure – we'll see when the time comes.)

Comment by Michał Marczyk [ 09/Dec/14 2:06 PM ]

I should say that it'd be possible to add generic support for any "vector lookalikes" by pouring them into regular vectors in linear time. At first glance it seems to me that that'd be out of line with the basic promise of the library, but I'll give it some more thought before the changes actually land.

Comment by Zach Tellman [ 09/Dec/14 5:43 PM ]

Somewhat predictably, the day after I cut the previous patch, someone found an issue [1]. In short, my use of the ArrayChunk wrapper applied the offset twice.

This was not caught by collection-check, which has been updated to catch this particular failure. It was, however, uncovered by Michael Blume's attempts to merge the change into Clojure, which tripped a bunch of alarms in Clojure's test suite. My own attempt to do the same to "prove" that it worked was before I added in the chunked seq functionality, hence this issue persisting until now.

As always, there may be more issues lurking. I hope we can get as many eyeballs on the code between now and 1.8 as possible.

[1] https://github.com/ztellman/cambrian-collections/commit/2e70bbd14640b312db77590d8224e6ed0f535b43
[2] https://github.com/MichaelBlume/clojure/tree/test-vector

Comment by Zach Tellman [ 10/Jul/15 1:54 PM ]

As a companion to the performance analysis in the unrolled map issue, I've run the benchmarks and posted the results at https://gist.github.com/ztellman/10e8959501fb666dc35e. Some notable results:

Comment by Alex Miller [ 13/Jul/15 9:02 AM ]

Stu: I do not think this patch should be marked "screened" until the actual integration and build work (if the generator is integrated) has been completed.

Comment by Alex Miller [ 14/Jul/15 4:33 PM ]

FYI, we have "reset" all big features for 1.8 for the moment (except the socket repl work). We may still include it - that determination will be made later.

Comment by Zach Tellman [ 14/Jul/15 4:43 PM ]

Okay, any idea when the determination will be made? I was excited that we seemed to be finally moving forward on this.

Comment by Alex Miller [ 14/Jul/15 4:51 PM ]

No, but it is now on my work list.

Comment by Rich Hickey [ 15/Jul/15 8:17 AM ]

I wonder if all of the overriding of APersistentVector yields important benefits - e.g. iterator, hashcode etc.

Comment by Zach Tellman [ 15/Jul/15 11:51 AM ]

In the case of hashcode, definitely: https://gist.github.com/ztellman/10e8959501fb666dc35e#file-gistfile1-txt-L1013-L1076. This was actually one of the original things I wanted to speed up.

In the case of the iterator, probably not. I'd be fine removing that.

Comment by Zach Tellman [ 16/Jul/15 5:17 PM ]

So am I to infer from https://github.com/clojure/clojure/commit/36d665793b43f62cfd22354aced4c6892088abd6 that this issue is defunct? If so, I think there's a lot of improvements being left on the table for no particular reason.

Comment by Rich Hickey [ 16/Jul/15 6:34 PM ]

Yes, that commit covers this functionality. It takes a different approach from the patch in building up from a small core, and maximizing improvements to the bases rather than having a lot of redundant definitions per class. That also allowed for immediate integration without as much concern for correctness, as there is little new code. It also emphasizes the use case for tuples, e.g. small vectors used as values that won't be changed, thus de-emphasizing the 'mutable' functions. I disagree that many necessary improvements are being left out. The patch 'optimized' many things that don't matter. Further, there are not big improvements to the pervasive inlining. In addition, the commit includes the integration work at a fraction of the size of the patch. In all, it would have taken much more back and forth to get the patch to conform with this approach than to just get it all done, but I appreciate the inspiration and instigation - thanks!

Comment by Rich Hickey [ 16/Jul/15 6:46 PM ]

That said, this commit need not be the last word - it can serve as a baseline for further optimization. But I'd rather that be driven by need. Clojure could become 10x as large optimizing things that don't matter.

Comment by Zach Tellman [ 19/Jul/15 1:36 PM ]

What is our reference for "relevant" performance? I (or anyone else) can provide microbenchmarks for calculating hashes or whatever else, but that doesn't prove that it's an important improvement. I previously provided benchmarks for JSON decoding in Cheshire, but that's just one of many possible real-world benchmarks. It might be useful to have an agreed-upon list of benchmarks that we can use when debating what is and isn't useful.

Comment by Mike Anderson [ 19/Jul/15 11:14 PM ]

I was interested in this implementation so created a branch that integrates Zach's unrolled vectors on top of clojure 1.8.0-alpha2. I also simplified some of the code (I don't think the metadata handling or unrolled seqs are worthwhile, for example)

Github branch: https://github.com/mikera/clojure/tree/clj-1517

Then I ran a set of micro-benchmarks created by Peter Taoussanis

Results: https://gist.github.com/mikera/72a739c84dd52fa3b6d6

My findings from this testing:

  • Performance is comparable (within +/- 20%) on the majority of tests
  • Zach's approach is noticeably faster (by 70-150%) for 4 operations (reduce, mapv, into, equality)

My view is that these additional optimisations are worthwhile. In particular, I think that reduce and into are very important operations. I also care about mapv quite a lot for core.matrix (It's fundamental to many numerical operations on arrays implemented using Clojure vectors).

Happy to create a patch along these lines if it would be acceptable.

Comment by Zach Tellman [ 19/Jul/15 11:45 PM ]

The `reduce` improvements are likely due to the unrolled reduce and kvreduce impls, but the others are probably because of the unrolled transient implementation. The extra code required to add these would be pretty modest.

Comment by Mike Anderson [ 20/Jul/15 9:20 PM ]

I actually condensed the code down to a single implementation for `Transient` and `TupleSeq`. I don't think these really need to be fully unrolled for each Tuple type. That helps by making the code even smaller (and probably also helps performance, given JVM inline caching etc.)

Comment by Peter Taoussanis [ 21/Jul/15 11:46 AM ]

Hey folks,

Silly question: is there actually a particular set of reference benchmarks that everyone's currently using to test the work on tuples? It took me a while to notice how bad the variance was with my own set of micro benchmarks.

Bumping all the run counts up till the noise starts ~dying down, I'm actually seeing numbers now that don't seem to agree with others here .

Google Docs link: https://docs.google.com/spreadsheets/d/1QHY3lehVF-aKrlOwDQfyDO5SLkGeb_uaj85NZ7tnuL0/edit?usp=sharing
gist with the benchmarks: https://gist.github.com/ptaoussanis/0a294809bc9075b6b02d

Thanks, cheers!

Comment by Zach Tellman [ 21/Jul/15 6:52 PM ]

Hey Peter, I can't reproduce your results, and some of them are so far off what I'd expect that I have to think there was some data gathering error. For instance, the assoc operation being slower is kind of inexplicable, considering the unrolled version doesn't do any copying, etc. Also, all of your numbers are significantly slower than the ones on my 4 year old laptop, which is also a bit strange.

Just to make sure that we're comparing apples to apples, I've adapted your benchmarks into something that pretty-prints the mean runtime and variance for 1.7, 1.8-alpha2, and Mike's 1517 fork. It can be found at https://github.com/ztellman/tuple-benchmark, and the results of a run at https://gist.github.com/ztellman/3701d965228fb9eda084.

Comment by Mike Anderson [ 22/Jul/15 2:24 AM ]

Hey Zach just looked at your benchmarks and they are definitely more consistent with what I am seeing. The overall nanosecond timings look about right from my experience with similar code (e.g. working with small vectors in vectorz-clj).

Comment by Peter Taoussanis [ 22/Jul/15 2:41 AM ]

Hi Zach, thanks for that!

Have updated the results -
Gist: https://gist.github.com/ptaoussanis/0a294809bc9075b6b02d
Google docs: https://goo.gl/khgT83

Note that I've added an extra sheet/tab to the Google doc for your own numbers at https://gist.github.com/ztellman/3701d965228fb9eda084.

Am still struggling to produce results that show any consistent+significant post-JIT benefit to either of the tuple implementations against the micro benchmarks and one larger small-vec-heavy system I had handy.

It's looking to me like it's maybe possible that the JIT's actually optimising away most of the non-tuple inefficiencies in practice?

Of course it's very possible that my results are off, or my expectations wrong. The numbers have been difficult to pin down.

It definitely helped to have a standardised reference micro benchmark to work against (https://github.com/ztellman/tuple-benchmark). Could I perhaps suggest a similar reference macro benchmark (maybe something from core.matrix, Mike?)

Might also be a good idea to define a worthwhile target performance delta for ops like these that run in the nanosecond range (or for the larger reference macro benchmark)?

Just some thoughts from someone passing through in case they're at all useful; know many of you have been deeply involved in this for some time so please feel free to ignore any input that's not helpful

Appreciate all the efforts, cheers!

Comment by Rich Hickey [ 22/Jul/15 9:24 AM ]

I think everyone should back off on their enthusiasm for this approach. After much analysis, I am seeing definite negative impacts to tuples, especially the multiple class approach proposed by Zach. What happens in real code is that the many tuple classes cause call sites that see different sized vectors to become megamorphic, and nothing gets adequately optimized. In particular, call sites that will see tuple-sized and large vectors (i.e. a lot of library code) will optimize differently depending upon which they see often first. So, if you run your first tight loop on vector code that sees tuples, that code could later do much worse (50-100%) on large vectors than before the tuples patch was in place. Being much slower on large collections is a poor tradeoff for being slightly faster on small ones.

Certainly different tuple classes for arity 0-6 is a dead idea. You get as good or better optimization (at some cost in size) from a single class e.g. one with four fields, covering sizes 0-4. I have a working version of this in a local branch. It is better in that sites that include pvectors are only bi-morphic, but I am still somewhat skittish given what I've seen.

The other takeaway is that the micro benchmarks are nearly worthless for detecting these issues.

Comment by Zach Tellman [ 22/Jul/15 11:07 AM ]

I'm pretty sure that all of my real-world applications of the tuples (via clj-tuple) have been fixed cardinality, and wouldn't have surfaced any such issue. Thanks for putting the idea through its paces.

Comment by Mike Anderson [ 22/Jul/15 10:37 PM ]

Rich these are good insights - do you have a benchmark that you are using as representative of real world code?

I agree that it is great if we can avoid call sites becoming megamorphic, though I also believe the ship has sailed on that one already when you consider the multiple types of IPersistentVector that already exist (MapEntry, PersistentVector, SubVector plus any library-defined IPersistentVector instances such as clojure.core.rrb-vector). As a consequence, the JVM is usually not going to be able to prove that a specific IPersistentVector interface invocation is monomorphic, which is when the really big optimisations happen.

In most of the real world code that I've been working with, the same size/type of vector gets used repeatedly (Examples: iterating over map entries, working with a sequence of size-N vectors), so in such cases we should be able to rely on the polymorphic inline cache doing the right thing.

The idea of a single Tuple class for sizes 0-4 is interesting, though I can't help thinking that a lot of the performance gain from this may stem from the fact that a lot of code does stuff like (reduce conj [] .....) or the transient equivalent which is a particularly bad use case for Tuples, at least from the call site caching perspective. There may be a better way to optimise such cases rather than simply trying to make Tuples faster.... e.g. calling asTransient() on a Tuple0 could perhaps switch straight into the PersistentVector implementation.

Comment by Colin Fleming [ 18/May/16 8:32 PM ]

Here's a relevant issue from Google's Guava project, where they also found serious performance degradation with fixed-size collections: https://github.com/google/guava/issues/1268. It has a lot of interesting detail about how the performance breaks down.

[CLJ-1929] Can't typehint literal collection to avoid reflection on Java interop call Created: 16/May/16  Updated: 18/May/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Defect Priority: Major
Reporter: David Bürgin Assignee: Unassigned
Resolution: Unresolved Votes: 1
Labels: interop, reflection, typehints

OS X 10.11.4

Attachments: Text File 0001-CLJ-1929-preserve-type-hints-in-literals.patch    
Patch: Code
Approval: Triaged


There is a reflection warning when passing a Clojure collection to a method that has a parameter of a collections interface type like java.util.Map.

Example calling java.time.format.DateTimeFormatterBuilder.appendText(java.time.temporal.TemporalField, java.util.Map):

(import 'java.time.format.DateTimeFormatterBuilder

(set! *warn-on-reflection* true)

(let [builder (DateTimeFormatterBuilder.)]
  (.appendText builder ChronoField/YEAR {}))
; Reflection warning, NO_SOURCE_PATH:6:3 - call to method appendText on java.time.format.DateTimeFormatterBuilder can't be resolved (argument types: java.time.temporal.ChronoField, clojure.lang.IPersistentMap).

The map literal cannot be hinted:

(let [builder (DateTimeFormatterBuilder.)]
  (.appendText builder ChronoField/YEAR ^java.util.Map {}))
; Reflection warning, NO_SOURCE_PATH:8:3 - call to method appendText on java.time.format.DateTimeFormatterBuilder can't be resolved (argument types: java.time.temporal.ChronoField, clojure.lang.IPersistentMap).

The warning does not appear when the map is not empty:

(let [builder (DateTimeFormatterBuilder.)]
  (.appendText builder ChronoField/YEAR {1 "a"}))

Nor does it appear on similar methods where there is no overloaded method with the same arity:

(let [builder (DateTimeFormatterBuilder.)]
  (.appendZoneText builder TextStyle/FULL #{}))

Workaround is to not use a literal:

(let [builder (DateTimeFormatterBuilder.)]
  (.appendText builder ChronoField/YEAR ^java.util.Map (array-map)))

It should be possible to infer in these cases like elsewhere that {} implements java.util.Map.

If that is not viable a type hint on {} should be honored.

Approach: preserve user hints in literal collections
Patch: 0001-CLJ-1929-preserve-type-hints-in-literals.patch

[CLJ-1063] Missing dissoc-in Created: 07/Sep/12  Updated: 18/May/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.4
Fix Version/s: None

Type: Enhancement Priority: Major
Reporter: Gunnar Völkel Assignee: Unassigned
Resolution: Unresolved Votes: 9
Labels: None

Attachments: File 001-dissoc-in.diff     Text File clj-1063-add-dissoc-in-patch-v2.txt    
Patch: Code and Test
Approval: Triaged


There is no clojure.core/dissoc-in although there is an assoc-in.
It is correct that dissoc-in can be build with update-in and dissoc but this is an argument against assoc-in as well.
When a shortcut for assoc-in is provided, there should also be one for dissoc-in for consistency reasons.
Implementation is analogical to assoc-in.

Comment by Andy Fingerhut [ 13/Sep/12 2:17 PM ]

Patch clj-1063-add-dissoc-in-patch-v2.txt dated Sep 13 2012 supersedes 001-dissoc-in.diff dated Sep 7 2012. It fixes a typo (missing final " in doc string), and adds a test case for the new function.

Comment by Nicola Mometto [ 13/Sep/12 2:27 PM ]

Thanks for the fix Andy

Comment by Andy Fingerhut [ 14/Sep/12 8:24 PM ]

This proposed dissoc-in should be compared with the one in clojure.core.incubator which I just happened across. I see they look different, but haven't examined to see if there are any behavior differences.


Comment by Nicola Mometto [ 15/Sep/12 6:43 AM ]

dissoc-in in clojure.core.incubator recursively removes empty maps

user=> (clojure.core.incubator/dissoc-in {:a {:b {:c 1}}} [:a :b :c])

while the one in this patch doesn't (as I would expect)

user=> (dissoc-in {:a {:b {:c 1}}} [:a :b :c])
{:a {:b {}}}

Comment by Stuart Halloway [ 17/Sep/12 7:04 AM ]

Please do this work in the incubator.

Comment by Andrew Rosa [ 30/Jun/15 9:09 AM ]

Keeping the empty paths is really the most expected thing to do? I say, since both assoc-in/update-in create paths along the way this behavior looks to be the real "dual".

What kind of bad things could happen that nil punning does not deal well with it? Those issues would be too much obscure for dissoc-in user's point of view?

Comment by Alex Miller [ 19/Oct/15 10:21 PM ]

Tests are much too light in the patch. Should test multiple levels, records, vectors, etc.

Comment by Daniel Compton [ 21/Oct/15 4:16 PM ]

Testing "clj-1063-add-dissoc-in-patch-v2.txt"

(dissoc-in {} [:a :b :c])
=> {:a {:b nil}}

this behaviour is pretty unexpected. The incubator version doesn't have this problem, though it does remove empty maps.

I'm working on tests (and possibly a new dissoc-in) for this patch, but I'm not clear yet whether empty paths should be kept or removed? I don't mind either way, though I tend to agree with Andrew Rosa that keeping them is more symmetrical.

Comment by Daniel Compton [ 16/May/16 4:12 PM ]

@alex, do you want empty paths to be kept or removed? Either way is acceptable, though on balance I slightly prefer leaving them. I can work up tests for this, once I know which direction you want to go in.

Comment by Alex Miller [ 17/May/16 6:46 AM ]

What are the tradeoffs of one vs the other?

In places where people are using dissoc-in stand-ins (update-in with dissoc etc) what behavior are they expecting?

Comment by Michał Marczyk [ 17/May/16 12:31 PM ]

If we only wanted to handle maps nested in maps …, I'd probably prefer removing empty subpaths.

However, if we want to admit vectors along the way, then leaving empty paths in place makes for pretty clear semantics in that case:

(dissoc-in [{:foo 1}] [0 :foo])
;= [{}]

In contrast, removing empty paths would seem to lead to problems that would have to be resolved either by limiting the path-removing behaviour to maps or throwing when a subpath nested in a vector becomes entry. Either approach seems suboptimal.

Comment by Michał Marczyk [ 17/May/16 12:38 PM ]

Also we could technically accept a flag to decide whether empty paths should be removed and let the user ensure that they only pass true if there are no vectors in the way. I'm not sure I like this approach very much, though, because it seems to me that the more natural purpose for extra arguments is to provide additional paths to dissoc for matching variadic dissoc and dissoc-in semantics (cf. CLJ-1771).

Comment by Alex Miller [ 18/May/16 8:12 AM ]

We must consider vectors or associative data structures other than maps. I also would prefer not to have a flag and to instead leave it open for variadic to remove multiple.

With an equivalent like:

(update-in [{:foo 1}] [0] dissoc :foo)

we would be left with [{}] so the existing way to do this does leave empty collections.

I also looked at some of the existing dissoc-in implementations that already exist - core.incubator, taoensso.encore, clj-http, medley, useful, plumbing, etc. Most work with a single key-path and leave empty collections - these seem largely to derive from the incubator version. The encore one works with multiple paths by separating the key path from the final leaf keys to dissoc (variadic). The medley, useful, and plumbing ones are map-only and remove empty maps.

I can't imagine that we would make a map-specific version of this in core (since all the other -in functions are generic) and thus I conclude that we would need a dissoc-in that left empty collections. Given that, I'm not sure whether dissoc-in provides enough value over update-in + dissoc to be worth adding to core at this point, especially since it exists in a variety of utility libraries (in many cases with differing semantics). We are then potentially breaking (or at least inconveniencing) many users of existing dissoc-in impls. I'm going to leave this open for comments, but I'm of a mind to decline this enhancement at this point.

Comment by Nicola Mometto [ 18/May/16 8:33 AM ]

The same argument could've been made for the inclusion of `update`. The fact that both `update` and `dissoc-in` can be found in several util libraries should indicate that people are not ok with just using `update-in` + `dissoc`.

Sure adding it to core is going to cause warnings when using some libraries (it's not going to break anything, the AOT bugs that caused breakages with `update` have been fixed) but I don't think that's really a big deal; new versions of those libraries will get released quickly and even if that's not the case a warning is not the end of the world.

Comment by Alex Miller [ 18/May/16 9:05 AM ]

True, although I'd say the factors balance differently in the update case. With update there fewer implementations and they matched what we were proposing to add. So, they created the potential for the existing ones to be replaced with a core function.

I think the common utility library impls (flatland/useful/plumbing) are actually covering a need that is different - update-in + dissoc + path removal on maps only. So if the goal is to cover a common usage, then we would need to have it work only on maps and remove empty paths left behind. However, I think that is somewhat at odds with the other core -in functions. I guess maybe there is a middle ground to do path removal but make it work beyond maps - that would satisfy the needs indicated by the utility libs but also be generic like the other -in functions. And if you needed to leave the empty colls, you could do what you do now - update-in+dissoc.

[CLJ-1206] 'eval' of closures or fns with runtime metadata within a call expr yields "No matching ctor found" exceptions Created: 28/Apr/13  Updated: 15/May/16  Resolved: 13/May/16

Status: Closed
Project: Clojure
Component/s: None
Affects Version/s: Release 1.5
Fix Version/s: None

Type: Defect Priority: Minor
Reporter: Jason Wolfe Assignee: Unassigned
Resolution: Declined Votes: 3
Labels: None


I ran into some issues with 'eval' when writing compilation strategies for Graph. It seems these may have been known for some time [1], but I couldn't find a ticket for them, so here we are.

Clojure docs [2] say "If the operator is not a special form or macro, the call is considered a function call. Both the operator and the operands (if any) are evaluated, from left to right," and "Any object other than those discussed above will evaluate to itself." While bare fns do seem to evaluate to themselves in all cases, when in a call expression, the evaluation of the operator fails on fn objects that are closures or have run-time metadata applied:

;; raw non-closures are fine
user> (eval (fn [x] (inc x)))
#<user$eval30559$fn_30560 user$eval30559$fn_30560@354ee11c>

;; raw closures are fine
user> (eval (let [y 1] (fn [x] (+ x y))))
#<user$eval30511$fn_30512 user$eval30511$fn_30512@3bac3a34>

;; non-closures in exprs are fine
user> (eval `(~(fn [x] (inc x)) 1))

;; but closures in exprs cause an error
user> (eval `(~(let [y 1] (fn [x] (+ x y))) 1))
IllegalArgumentException No matching ctor found for class user$eval30535$fn__30536 clojure.lang.Reflector.invokeConstructor (Reflector.java:163)

;; as do fns with metadata in exprs
user> (eval `(~(with-meta (fn [x] (inc x)) {:x 1}) 1))
IllegalArgumentException No matching ctor found for class clojure.lang.AFunction$1 clojure.lang.Reflector.invokeConstructor (Reflector.java:163)

[1] http://stackoverflow.com/a/11287181
[2] http://clojure.org/evaluation

Comment by Dmitri Gaskin [ 17/Feb/16 9:25 PM ]

I have run into this as well. I ran into it while using https://github.com/plumatic/schema + a memoized predicate function + https://github.com/metosin/compojure-api. After hours of debugging, I was able to narrow it down to:

user=> (let [foo inc] (eval `(~foo 1)))
user=> (let [foo (memoize inc)] (eval `(~foo 1)))

IllegalArgumentException No matching ctor found for class clojure.core$memoize$fn__5708 clojure.lang.Reflector.invokeConstructor (Reflector.java:163)

Comment by Kevin Downey [ 17/Feb/16 11:01 PM ]

basically, this cannot work. as it stands now, for some set of fn objects (including closures) eval fails, because the compiler cannot embed arbitrary function objects in the emitted bytecode. for another set of fn objects eval succeeds, because there is a fall back in eval, where it tries to embed arbitrary objects in the byte code by invoking a no argument constructor on the class of the object. closures fail to work in that fall back because the classes generated for fns that are closures in clojure don't have 0-arg constructors.

don't eval function objects

Comment by Kevin Downey [ 17/Feb/16 11:20 PM ]

for a work around maybe try using dynamic binding?

Comment by Jason Wolfe [ 18/Feb/16 12:35 AM ]

Here is a workaround that we use in graph: https://github.com/plumatic/plumbing/blob/master/src/plumbing/graph/positional.clj#L45

Basically, rather than evaluating a form with function objects inside, e.g. `(eval (... f))`, we do: `((eval (fn [x] (... x))) f)`.

Comment by Steve Miner [ 11/May/16 3:08 PM ]

I've worked around someting like this using `intern`. My situation was a bit different as I was trying to use macros to precompile some calculations into a function to be called at runtime. My first attempt was to embed the actual function, which of course gave me the "no matching ctor" error.

Rewriting the original problem, and introducing a scratch var tmp_42, we have:

(eval `(~(let [y 1] (intern *ns* 'tmp_42 (fn [x] (+ x y)))) 1))
;=> 2

Note, intern returns the new var so we just return that as our function to be called. Maybe you'd want to use (gensym) instead of tmp_42 to be safer. And maybe you'd want to use a different namespace. The main point is that using a var to hold the function makes it easier to access in a different context.

Comment by Nicola Mometto [ 13/May/16 5:28 AM ]

I personally don't think this should be considered a bug at all.
The docstring for eval explicitely states that eval takes a data structure, a function object is not a data structure and thus should not be expected to be evaluable.

Comment by Alex Miller [ 13/May/16 8:25 AM ]

Yeah, I've reached essentially the same conclusion.

Comment by Kevin Downey [ 13/May/16 1:19 PM ]

if anything the bug is that it works with some function objects and not with others

Comment by Richard Davies [ 13/May/16 9:44 PM ]

I agree with Kevin's last comment - if this bug is closed because functions are not valid data structures, then the cases where some functions do work would therefore be a bug.

Secondly, the error message is unhelpful. "No matching ctor found" should be replaced with something close to the actual cause such as "a function is not valid data structures for eval" or something similar.

Comment by Jason Wolfe [ 14/May/16 1:32 AM ]

Much of my initial confusion stemmed from http://clojure.org/reference/evaluation, which still ends with "Any object other than those discussed above will evaluate to itself" – which seems to contradict the "data structure" viewpoint of eval.

Comment by Jason Wolfe [ 14/May/16 4:17 AM ]

To clarify, I don't particularly care either way (although it would make some rare instances more convenient if this worked). It just seems like this is a bit of a dark corner currently, so if the behavior isn't going to change, should I open an issue on https://github.com/clojure/clojure-site/blob/master/content/reference/evaluation.adoc instead? (I would offer to submit a PR, but I'm not quite clear on where the lines between "evaluates to itself", "errors", and "one of the above / UB" should be drawn.)

Comment by Alex Miller [ 14/May/16 6:54 AM ]

@Richard - if someone wanted to file a ticket for the error message in this case, I think that would be reasonable. I can't imagine we would make something that works now stop working. I see your point and all, just in the grand scheme of how we spend our time, that does not seem to make sense to me.

@Jason - probably best just to file an issue so I can run something by Rich eventually.

Comment by Jason Wolfe [ 15/May/16 3:31 AM ]

Thanks Alex, I just opened https://github.com/clojure/clojure-site/issues/95

Comment by Richard Davies [ 15/May/16 6:04 AM ]

Fair enough Alex. Opened http://dev.clojure.org/jira/browse/CLJ-1928

[CLJ-1928] Provide meaning error message when eval of function fails. Created: 15/May/16  Updated: 15/May/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Defect Priority: Minor
Reporter: Richard Davies Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: errormsgs



When attempting to eval a function, in some cases this fails with "No matching ctor found". This error does not clearly indicate the root cause. Suggest something like "cannot eval function" or something similar. See http://dev.clojure.org/jira/browse/CLJ-1206 for history relating to this ticket.

[CLJ-1911] min-key and max-key should return NaN if any of the argument is NaN Created: 08/Apr/16  Updated: 12/May/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Defect Priority: Minor
Reporter: Renzo Borgatti Assignee: Unassigned
Resolution: Unresolved Votes: 3
Labels: None

Likely All. Including older version of Clojure.

Attachments: Text File CLJ-1911-contagious-NaN-and-tests.patch     Text File CLJ-1911-contagious-NaN.patch     Text File CLJ-1911-NaN-fix-over-CLJ-99.patch    
Patch: Code
Approval: Triaged


It appears that min-key and max-key behave incorrectly (following Java that follows IEEE floating point convention):

(apply max-key last [[:a 10000] [:b (/ 0. 0)] [:c 0]])
[:c 0]

Not sure how this should then propagate forward, but definitely not silently. Options:

1. [:b NaN] (the first item to generate the NaN)
2. NaN (this is changing the expected type)
3. ArithmeticException Operation with at least one NaN operand.

If this was to be patched the same as it was for min/max (http://dev.clojure.org/jira/browse/CLJ-868) it will probably result in option 1.

Comment by Nicholas Antonov [ 14/Apr/16 9:36 PM ]

This implements the first solution of a contagious NaN in the same style as CLJ 868

Comment by Alex Miller [ 15/Apr/16 12:03 AM ]

Patch should have tests...

Comment by Nicholas Antonov [ 15/Apr/16 1:07 AM ]

This latest patch adds tests for min-key and max-key with and without NaN results, as there were none before.

Comment by Alex Miller [ 29/Apr/16 10:06 AM ]

This overlaps with CLJ-99, which has already been prescreened. I would like to base whatever changes this patch requires over the top of that ticket. To build this, apply the CLJ-99 patch, then branch, make you changes, and then create a patch relative to the clj-99 branch. Sorry that's a pain - usually patches don't collide at this level of conflict.

Comment by Nicholas Antonov [ 12/May/16 6:14 AM ]

The latest patch fixes min and max key in the same way, but based over CLJ-99, only evaluating the function once for each item.

[CLJ-1925] Add uuid and random-uuid functions Created: 10/May/16  Updated: 11/May/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Enhancement Priority: Minor
Reporter: Daniel Compton Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: function


ClojureScript has uuid and random-uuid functions. These are handy to have in ClojureScript, and I think would be useful also in Clojure to improve code portability. Is there interest in a patch for this?

Comment by Alex Miller [ 10/May/16 8:00 AM ]

I think the main reason to do this would be portability. It would make most sense to generate java.util.UUIDs - is that harmonious with what is being done in ClojureScript? That is, could the same code for creating and using uuids work on both platforms? If not, then there might not be a good reason to do so.

Comment by Daniel Compton [ 10/May/16 3:45 PM ]

> It would make most sense to generate java.util.UUIDs - is that harmonious with what is being done in ClojureScript?

ClojureScript defines it's own UUID type, as one doesn't exist in JavaScript. https://github.com/clojure/clojurescript/blob/dd589037f242b4eaace113ffa28ab7b3791caf47/src/main/cljs/cljs/core.cljs#L10088-L10128. I'm not quite sure what you mean by harmonious.

> That is, could the same code for creating and using uuids work on both platforms?

The CLJS UUID doesn't support all of the methods of the Java UUID, but the important things are there (equivalence, constructing from a string, printing to a string) and they would be enough to significantly improve portability when working with UUID's.

Comment by Nicola Mometto [ 10/May/16 4:27 PM ]

both clojure and clojurescript have uuid tagged literals, that should be good enough for interop

Comment by Alex Miller [ 11/May/16 2:48 PM ]

I'm aware of that, just wondering if there are any functions you might invoke on a uuid that would need some portable equivalent, like the stuff in http://docs.oracle.com/javase/8/docs/api/java/util/UUID.html.

Comment by Daniel Compton [ 11/May/16 3:27 PM ]

Most of the extra methods here are useful for distinguishing between multiple types of UUID's, or getting information out of time based UUIDs.

clockSequence() - time based
compareTo(UUID val) - not sure if equivalent required?
boolean	equals(Object obj) - no action required
static UUID	fromString(String name) - constructor
long	getLeastSignificantBits() - not sure how important these two are
long	getMostSignificantBits()
int	hashCode() - no action required
static UUID	nameUUIDFromBytes(byte[] name) - is this useful/important?
long	node() - only useful for time UUID
static UUID	randomUUID() - would implement this
long	timestamp() - time based UUID
String	toString() - no action required
int	variant() - for distinguishing between different types of UUID's
int	version() - for distinguishing between different versions of UUID's

I could potentially see an argument for time based UUID's being included in a patch here too, but I'm not sure if they are used enough to be worth it, and they'd need to go into CLJS, e.t.c.

There is use of some of these methods in Clojure code:

But less than the literal constructor by a factor of ~100:
https://github.com/search?utf8=✓&q=java+util+UUID+language%3Aclojure&type=Code&ref=searchresults (this is a flawed search query, but the best I could do).

Comment by Alex Miller [ 11/May/16 3:56 PM ]

I guess my greater point is: rather than consider just the functions uuid/random-uuid, let's consider the problem to be: how can we add portable uuid support in Clojure/ClojureScript? That's a lot more work, but a lot more valuable in my opinion.

So would also want to consider (some of these exist already, but may not have been tested for portability):

  • construction
  • printing - print, pr, pretty print
  • reading
  • hash code
  • conversion to/from bits
  • conversion to/from string
  • extraction of components

And then I think it's worth considering how much of this should be in core vs in a data.uuid or something.

I think it's probably better to work it off a design page than here (this ticket is but one unit of the greater problem). Perhaps http://dev.clojure.org/pages/viewpage.action?pageId=950382 could suggest some pointers.

[CLJ-1906] Clojure should make representing iterated api calls easier Created: 30/Mar/16  Updated: 10/May/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Enhancement Priority: Minor
Reporter: Kevin Downey Assignee: Unassigned
Resolution: Unresolved Votes: 3
Labels: None

Attachments: Text File 0001-CLJ-1906-add-ingeminate-function.patch     Text File 0001-CLJ-1906-add-unfold-function.patch     Text File 0001-CLJ-1906-transducer-enabled-iterate.patch     File CLJ-1906-seqable-reducible.diff    


Many apis (elasticsearch, github, s3, etc) have parts of the api
which, in usage, end up being used in an interative way. You make an
api call, and you use the result to make another api call, and so
on. This most often shows up in apis have some concept of pages of
results that you page through, and is very prevalent in http apis.

This appears to be such a common pattern that it would be great if
Clojure had in built support for it.

You may think Clojure already does have support for it, after all,
Clojure has `iterate`. In fact the docstring for `iterate`
specifically says the function you give it must be free of side

I propose adding a function `unfold` to clojure.core to support this
use case. `unfold` would return an implementation of ReduceInit. The
name `unfold` matches what would be a similar Haskell function
and also matches the name for a similar function used in some existing
Clojure libraries

`unfold` in some ways looks like a combination of `take-while` and
`iterate`, except for the fact that `iterate` requires a pure
function. Another possible solution would be a version of `iterate`
that doesn't require a pure function.

It seems like given the use case I envision for `unfold`, a
non-caching reducible would be perfect. But that would leave those
that prefer seqs high and dry, so maybe at least some consideration
should be given to seqs.

Mailing list discussion is here

A sort of dummy api you might want to interact with would look something like

(import '(java.util UUID))

(def uuids (repeatedly 1000 #(UUID/randomUUID)))

(def uuid-index
  (loop [uuids uuids
         index  {}]
    (if (seq uuids)
      (recur (rest uuids) (assoc index (first uuids) (rest uuids)))

(defn api
  "pages through uuids, 10 at a time. a list-from of :start starts the listing"
  (let [page (take 10 (if (= :start list-from)
                        (get uuid-index list-from)))]
    {:page page
     :next (last page)}))

given the above api, if you had an implementation of `unfold` that took a predicate that decided when to continue unfolding, a producer which given a value in a sequence produced the next value, and an initial value, you could do something like this:

(= uuids (into [] (mapcat :page) (unfold :next (comp api :next) (api :start))))

and the result would be true.

The equivilant take-while + iterate would be something like:

;; the halting condition is not strictly the same
(= uuids (into [] (mapcat :page) (take-while (comp seq :page) (iterate (comp api :next) (api :start)))))

Comment by Kevin Downey [ 31/Mar/16 4:21 PM ]

I made two patches, one adds unfold as discussed above, one adds ingeminate which is like iterate but without the function purity restrictions, and doesn't return a seq.

Comment by Ghadi Shayban [ 11/Apr/16 10:46 AM ]

Though syntax is less important than the semantics, may I propose the name `progression` for this? Clojure's fold is called reduce, so unfold is too much like Haskell. Other names I was considering include evolve & derivations.

Comment by Alex Miller [ 11/Apr/16 11:23 AM ]

Another option would be `productions` (reminiscent of `reductions`).

Comment by Kevin Downey [ 11/Apr/16 9:32 PM ]

productions has a nice ring to it. emanate could work too, would sort near eduction

Comment by Ghadi Shayban [ 12/Apr/16 10:08 PM ]

Adding a patch with a generator impl that is clojure.lang.{Seqable,IReduceInit}.

Generative tests assert that the seq and reduce halves are equivalent.

Tests assert basic functionality, obeying reduced, and maximal laziness of the seq impl.

Docstring has been wordsmithed and the function named `productions`.

Comment by Kevin Downey [ 18/Apr/16 3:21 PM ]

apparently unfold is part of SRFI 1: List Library in scheme land http://srfi.schemers.org/srfi-1/srfi-1.html#FoldUnfoldMap

it looks like their unfold is take-while + iterate + map

Comment by Ghadi Shayban [ 23/Apr/16 11:06 PM ]

Main differences between Scheme's impl and this proposed one:
Predicate reversed (stop? vs continue?)
Scheme has a "mapping function" to produce a different value from the current seed, Clojure doesn't (but has transducers)
Scheme has an extra optional arg to build the tail of the list

Now I'm partial to the name successions.

Comment by Michał Marczyk [ 10/May/16 11:07 AM ]

I can confirm that I found unfold quite useful in my Scheme days.

In Clojure, this general pattern can be expressed using transducers at a modest cost in keystrokes:

(def numbers (doall (range 1000)))

(defn api [list-from]
  (if list-from
    (let [page (vec
                 (take 10 (if (= :start list-from)
                            (drop list-from numbers))))]
      {:page page
       :next (some-> (last page) inc)})))

(= numbers
   (sequence (comp (take-while some?)
                   (mapcat :page))
             (iterate (comp api :next)
                      (api :start))))
;= true

Maybe this could be simplified with an xform-enabled version of iterate?

(defn iterate*
  ([f seed]
   (iterate f seed))
  ([xform f seed]
   (sequence xform (iterate f seed))))

(= numbers
     (comp (take-while some?) (mapcat :page))
     (comp api :next)
     (api :start)))
;= true

Admittedly this takes more characters, but is quite generic and a transducer-enabled overload in iterate feels pretty natural to me. Attaching a simple patch implementing this in clojure.core/iterate – I'll look at clojure.lang.Iterate to see if it's worth implementing direct support later, unless of course nobody wants this.

Comment by Michał Marczyk [ 10/May/16 11:08 AM ]

0001-CLJ-1906-transducer-enabled-iterate.patch adds a ternary overload to iterate that delegates to the binary overload and sequence.

Comment by Ghadi Shayban [ 10/May/16 12:56 PM ]

A few unsatisfactory things about overloading {iterate}
1) iterate's docstring says {f must be free of side-effects}
2) There is boilerplate and subtlety around the terminating item. In this case the final API call is made unconditionally, leading to an extra empty/marker item that is filtered by take-while. With the current proposal, the predicate controls iteration from the inside out

[CLJ-1921] Wrong numeric result from Math/abs on Java 8 Created: 09/May/16  Updated: 10/May/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Defect Priority: Major
Reporter: Alex Miller Assignee: Unassigned
Resolution: Unresolved Votes: 1
Labels: math, reflection

does not seem specific to Clojure version
occurs only in Java 1.8


This is with Java 1.8 (Oracle or Open JDK):

weird-abs.core=> (Math/abs -10000000000000)
weird-abs.core=> (def a    -10000000000000)
weird-abs.core=> (Math/abs a)

In Java 1.7, the expected results are returned instead (10000000000000).

Cause: It appears that Math.abs(int) is being invoked. Both the int and long versions are considered by the reflector but Java 1.7 and 1.8 return these signatures in different orders and the first one found is picked.

Workaround: Use hint or cast to inform the reflector which one to pick.

Comment by Alex Miller [ 09/May/16 9:03 AM ]

In the first case, -10000000000000 is a long and the compiler unambiguously finds Math.abs(long).

In the second case, a is an Object and all abs signatures are considered (this is in Reflector.invokeMatchingMethod). In both Java 1.7 and 1.8, the long and int signatures are found "congruent".

In Java 1.7, the long version is found first and treated as a match, then int is checked and Compiler.subsumes([int], [long]) returns false, leading to the long method being kept as the match.

In Java 1.8, the int version is found first and treated as a match, then long is checked and Compiler.subsumes([long], [int]) returns false, leading to the int method being kept as the match.

Both of these return false on both JDKs:

(Compiler/subsumes (into-array [Long/TYPE]) (into-array [Integer/TYPE]))
(Compiler/subsumes (into-array [Integer/TYPE]) (into-array [Long/TYPE]))

so the real difference is just the ordering that is considered, which is JDK-specific.

The considered signatures could be sorted in some canonical way making this behavior consistent, or could maybe express a preference between the two signatures somehow.

In any case, getting rid of the reflection here by hinting or casting a resolves the problem - it should be considered only luck not intention that the correct results comes out with Java 7 in this case, I think.

Comment by Nicola Mometto [ 10/May/16 7:58 AM ]

It seems to me that the non-deterministic behaviour of clojure's reflector of randomly picking one overload when more than one is available is both highly counterintuitive and undesirable.

IMHO the only sane approach would be to:

  • pick the most specific type if possible (e.g. if what's available is [Object, CharSequence, String] and the reflected type is a StringBuffer, we use CharSequence rather than Object.
  • pick the widest primitive type if possible (e.g. in this case we'd use long rather than int)
  • Fail with a `More than one matching method found` exception if conflicts can't be resolved (this already happens in some cases)

(I'm still scarred from previous experiences of reading/patching the complex beast that is Reflector.java and the reflective bits of Compiler.java, so I propose this with no intention of ever working on this myself )

Comment by Alex Miller [ 10/May/16 8:03 AM ]

I think the subsumes check is effectively trying to do your option #1 already - this is a case where the types of the arguments in the two cases have no hierarchical relationship. Probably #2 would make more sense - expressing a preference, although there are certainly cases where "widest" has no meaning, so not sure what the general form of this is.

Comment by Nicola Mometto [ 10/May/16 8:05 AM ]

To clarify, that wasn't a list of different options, it was a list of steps to take.
i.e. if it's possible to pick the most specific type from a hierarchy, do that, ELSE if the types are primitive, pick the widest ELSE fail

[CLJ-1920] Create an easy way to gracefully shutdown agents Created: 03/May/16  Updated: 03/May/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Enhancement Priority: Major
Reporter: Ruslan Al-Fakikh Assignee: Ruslan Al-Fakikh
Resolution: Unresolved Votes: 1
Labels: agents


Currently there is no easy way to shutdown agents while making sure all the submitted actions are completed and no new actions are sent.

Here is the naive approach:


There are two problems with that:
1) It will discard all the actions that have already been submitted, but haven't been started.
2) It won't prohibit from sending further actions to agents (no explicit error will be thrown, just silent ignoring).

Here is the proof:

(def my-agent (agent 1))

(defn sleep-and-inc [number]
  (Thread/sleep 3000)
  (println "action number" number "complete")
  (inc number))

(println "sending off 2 times")
(send-off my-agent sleep-and-inc)
(send-off my-agent sleep-and-inc)
(println "sending off complete")

(println "shutdown requested")

(println "sending off a 3rd time")
(send-off my-agent sleep-and-inc)
(println "sending off complete")

Here is the output:

sending off 2 times
sending off complete
shutdown requested
sending off a 3rd time
sending off complete
action number 1 complete

As you can see - the 2nd action got discarded, the 3rd action got ignored.

And btw, the shutdown-agents' docstring is misleading (not clear):
"...Running actions will complete, but no new actions will be accepted"
1) It doesn't say anything about already submitted actions
2) "no new actions will be accepted" sounds like there should be an error, but it's silently ignored.
So, the better docstring should be "...Running actions will complete, waiting actions will be discarded and new actions will be ignored"

A similar naive approach works perfectly well in Java:

ExecutorService executor = Executors.newSingleThreadExecutor();

        executor.submit(new Runnable() {
            public void run() {
                try {
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                System.out.println("Action 1 complete");
        executor.submit(new Runnable() {
            public void run() {
                try {
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                System.out.println("Action 2 complete");

        System.out.println("Shutdown requested");

//        //will throw RejectedExecutionException
//        executor.submit(new Runnable() {
//            @Override
//            public void run() {
//                try {
//                    Thread.sleep(3000);
//                } catch (InterruptedException e) {
//                    throw new RuntimeException(e);
//                }
//                System.out.println("Action 3 complete");
//            }
//        });


Shutdown requested
Action 1 complete
Action 2 complete

By "perfectly well" I mean:
1) It will complete all the waiting tasks (not just running)
2) It will throw an error on a new task after "shutdown" was called.

So, back to Clojure - currently we are only left with this idiom (not trivial!):

(await my-agent)

It is not a trivial and straightforward idiom, because:
1) You need to keep track of all the agents in the system. Becomes close to impossible if you are dealing with third-party code that uses agents.
2) Still doesn't even throw an exception if you happen to send another action while waiting or shutting down.

(inspired by Java):
1) Create a new function called "shutdown-agents-gracefully" which will do 2 additional things:
1.1) Put the agents system to "shutting down" state
1.2) Completes the running actions as well as the waiting actions
2) Modify "send" and "send-off" so that they throw an error in case the agent system is in "shutting down" state.
3) Fix the docstring of "shutdown-agents" (see above)

I'll start developing a patch when this jira ticket is validated.

[CLJ-1402] sort-by calls keyfn more times than is necessary Created: 11/Apr/14  Updated: 29/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Enhancement Priority: Minor
Reporter: Steve Kim Assignee: Unassigned
Resolution: Unresolved Votes: 2
Labels: performance

Attachments: Text File CLJ-1402-v1.patch     Text File CLJ-1402-v2.patch    
Patch: Code
Approval: Triaged


clojure.core/sort-by evaluates keyfn for every pairwise comparison. This is wasteful when keyfn is expensive to compute.

user=> (def keyfn-calls (atom 0))
user=> (defn keyfn [x] (do (swap! keyfn-calls inc) x))
user=> @keyfn-calls
user=> (sort-by keyfn (repeatedly 10 rand))
(0.1647483850582695 0.2836687590331822 0.3222305842748623 0.3850390922996001 0.41965440953966326 0.4777580378736771 0.6051704988802923 0.659376178201709 0.8459820304223701 0.938863131161208)
user=> @keyfn-calls

Comment by Steve Kim [ 11/Apr/14 11:46 AM ]

CLJ-99 is a similar issue

Comment by Michael Blume [ 09/Feb/15 3:03 PM ]

Avoid using for before it's defined

Comment by Andy Fingerhut [ 25/May/15 5:13 PM ]

Michael, does your patch CLJ-1402-v2.patch intentionally modify the doc string of sort-by, because the sentence you are removing is now obsolete? If so, that would be good to mention explicitly in the comments here.

Comment by Michael Blume [ 26/May/15 2:41 PM ]

Yep, the patch changes sort-by so that it maps over the collection and then performs a sort on the resulting seq. This means arrays will be unmodified and a new seq created instead.

Comment by Alex Miller [ 29/Apr/16 10:10 AM ]

This patch seems like it could be slower, rather than faster, due to the extra allocation. Really needs perf tests before it can be seriously considered.

[CLJ-1647] infinite loop in 'partition' and 'partition-all' when 'step' or 'n' is not positive Created: 20/Jan/15  Updated: 27/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.6
Fix Version/s: None

Type: Defect Priority: Minor
Reporter: Kevin Woram Assignee: Unassigned
Resolution: Unresolved Votes: 1
Labels: checkargs, newbie

Attachments: Text File clj-1647_2.patch     Text File clj-1647_3.patch     Text File clj-1647.patch     Text File kworam-clj-1647.patch    
Patch: Code and Test
Approval: Prescreened


If you pass a non-positive value of 'n' or 'step' to partition, you get an infinite loop. Here are a few examples:

(partition 0 [1 2 3])
(partition 1 -1 [1 2 3])

Cause: partition and partition-all do not check that n and step are positive.

Approach: Add checks to partition and partition-all that n and step are positive.

Patch: clj-1647_3.patch

Prescreened by: Alex Miller

Comment by Alex Miller [ 03/Feb/15 5:34 PM ]

Also see CLJ-764

Comment by Alex Miller [ 29/Apr/15 12:02 PM ]

Needs a perf check when done.

Comment by Kevin Woram [ 16/May/15 1:58 PM ]

patch file to fix clj-1647

Comment by Kevin Woram [ 16/May/15 2:19 PM ]

Since 'n' and 'step' remain unchanged from the initial function call through all of the recursive self-calls, I only need to verify that they are positive once, on the initial call.

I therefore created functions 'internal-partition' and 'internal-partition-all' whose implementations are identical to the current versions of 'partition' and 'partition-all'.

I then added preconditions that 'step' and 'n' must be positive to the 'partition' and 'partition-all' functions, and made them call 'internal-partition' and 'internal-partition-all' respectively to do the work.

Comment by Alex Miller [ 17/May/15 8:14 AM ]

There are a lot of unrelated whitespace changes in this patch - can you supply a smaller patch with only the change at issue? Also needs tests.

Comment by Kevin Woram [ 17/May/15 2:05 PM ]

I will supply a patch file without the whitespace changes.

I know there are some existing functionality tests for 'partition' and 'partition-all' in test_clojure\sequences.clj and test_clojure\transducers.clj. I don't think I need to add more functionality tests, but I think I should add:

1. Tests that verify that non-positive 'step' and 'n' parameters are rejected.
2. Tests that show that 'partition' and 'partition-all' performance has not degraded significantly.

Could you give me some guidance on how to develop and add these tests?

Comment by Alex Miller [ 17/May/15 3:31 PM ]

You should add #1 to the patch. For #2, you can just do the timings before/after (criterium is a good tool for this) and put the results in the description.

Comment by Kevin Woram [ 22/May/15 4:04 PM ]

I have coded up the tests for #1 and taken some 'before' timings for #2 using criterium.

I have been stumped by a problem for hours now and I need to get some help. I made my changes to 'partition' and 'partition-all' in core.clj and then did 'mvn package' to build the jar. I executed 'target>java -cp clojure-1.7.0-master-SNAPSHOT.jar clojure.main' to test out my patched version of clojure interactively. The (source ...) function shows that my source changes for both 'partition' and 'partition-all' are in place. My change to 'partition-all' seems to be working but my change to 'partition' is not. As far as I can tell, they should both throw an AssertionError with the input parameters I am providing.

Any help would be greatly appreciated.

user=> (source partition)
(defn partition
"Returns a lazy sequence of lists of n items each, at offsets step
apart. If step is not supplied, defaults to n, i.e. the partitions
do not overlap. If a pad collection is supplied, use its elements as
necessary to complete last partition upto n items. In case there are
not enough padding elements, return a partition with less than n items."
{:added "1.0"
:static true}
([n coll]
{:pre [(pos? n)]}
(partition n n coll))
([n step coll]
{:pre [(pos? n) (pos? step)]}
(internal-partition n step coll))
([n step pad coll]
{:pre [(pos? n) (pos? step)]}
(internal-partition n step pad coll)))
user=> (partition -1 [1 2 3])
user=> (source partition-all)
(defn partition-all
"Returns a lazy sequence of lists like partition, but may include
partitions with fewer than n items at the end. Returns a stateful
transducer when no collection is provided."
{:added "1.2"
:static true}
([^long n]
(internal-partition-all n))
([n coll]
(partition-all n n coll))
([n step coll]
{:pre [(pos? n) (pos? step)]}
(internal-partition-all n step coll)))
user=> (partition-all -1 [1 2 3])
AssertionError Assert failed: (pos? n) clojure.core/partition-all (core.clj:6993)

Comment by Alex Miller [ 22/May/15 4:47 PM ]

Did you mvn clean? Or rm target?

Comment by Kevin Woram [ 24/May/15 11:46 PM ]

Yes, I did mvn clean and verified that clojure-1.7.0-master-SNAPSHOT.jar had the expected date-time stamp before doing the interactive test. I even went so far as to retrace my steps on my Macbook on the theory that maybe there was a Windows-specific build problem.

My change to partition-all works as expected but my change to partition does not. However, if I copy the result of the call to (source partition) and execute it (replacing clojure.core/partition with user/partition), user/partition works as expected. I don't understand why my change to clojure.core/partition isn't taking effect.

Comment by Andy Fingerhut [ 25/May/15 1:27 AM ]

Kevin, I do not know the history of your Clojure source tree, but if you ever ran 'ant' in it, that creates jar files in the root directory, whereas 'mvn package' creates them in the target directory. It wasn't clear from your longer comment above whether the 'java -cp ...' command you ran pointed at the one in the target directory. That may not be the cause of the issue you are seeing, but I don't yet have any guesses what else it could be.

Comment by Alex Miller [ 13/Jul/15 1:17 PM ]

What's the status of this?

Comment by Kevin Woram [ 16/Jul/15 10:20 PM ]

Alex, I moved to Seattle and took a permanent position with Microsoft recently. This has kept me very busy and I haven't been able to spend time on Clojure at all. I probably won't be able to devote time to Clojure for another month or two.

Comment by Alex Miller [ 16/Jul/15 10:46 PM ]

Thanks for the heads up.

Comment by Matthew Gilliard [ 23/Jul/15 2:51 PM ]

Kevin, Alex, I could pick this up if you like?

Comment by Alex Miller [ 23/Jul/15 8:40 PM ]

Go for it

Comment by Alex Miller [ 23/Jul/15 8:40 PM ]

Go for it

Comment by Alex Miller [ 23/Jul/15 8:40 PM ]

Go for it

Comment by Alex Miller [ 23/Jul/15 8:40 PM ]

Go for it

Comment by Alex Miller [ 23/Jul/15 8:41 PM ]

Sorry, browser fail

Comment by Kevin Woram [ 25/Jul/15 7:03 PM ]

Thanks for picking it up Matthew, I appreciate it!

Comment by Kevin Woram [ 25/Jul/15 7:03 PM ]

Thanks for picking it up Matthew, I appreciate it!

Comment by Matthew Gilliard [ 27/Jul/15 11:30 AM ]

New patch: clj-1647.patch

Includes tests, fewer whitespace changes, manually thrown IAEs. I'll do some basic benchmarking soon, although I expect the overhead to be quite low as we're only checking the arguments once.

Kevin, the reason your patch was working for partition-all but not partition is that partition is defined early-ish in the bootstrapping process and the {:pre .. :post ..} maps aren't read by defn until it's enhanced later on.

Comment by Kevin Woram [ 27/Jul/15 12:10 PM ]

Thanks for solving that mystery Matthew!

Comment by Alex Miller [ 10/Mar/16 2:45 PM ]

Patch looks basically good. Minor changes:

  • internal-partition and internal-partition-all should be marked private with defn-.
  • Commit description should start with "CLJ-1647"
Comment by Matthew Gilliard [ 26/Apr/16 10:32 AM ]

I added clj-1647_2.patch to supersede other patches on this issue. Jira ref is added to commit msg and defn- used where possible (defn- is not defined until after one of the private fns but there is the ^:private metadata added manually)

Comment by Alex Miller [ 26/Apr/16 11:42 AM ]

The patch changes add-annotation from defn- to defn but that seems unrelated to the intent of the patch?

Comment by Matthew Gilliard [ 27/Apr/16 3:15 AM ]

Thanks for looking so quickly Alex - sorry about that error in add-annotation. See clj-1647_3.patch

[CLJ-1768] quote of an empty lazyseq produces an error when evaled Created: 24/Jun/15  Updated: 26/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.7
Fix Version/s: None

Type: Defect Priority: Minor
Reporter: Tim Engler Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: None

Approval: Triaged

user=> (eval `'())
user=> `'~(map identity ())
(quote ())
user=> (eval `'~(map identity ()))    ;; expected: ()
CompilerException java.lang.UnsupportedOperationException: Unknown Collection type, compiling:(NO_SOURCE_PATH:5:1)
user=> (prn *e)
#error {
 :cause "Unknown Collection type"
 [{:type clojure.lang.Compiler$CompilerException
   :message "java.lang.UnsupportedOperationException: Unknown Collection type, compiling:(NO_SOURCE_PATH:5:1)"
   :at [clojure.lang.Compiler analyzeSeq "Compiler.java" 6730]}
  {:type java.lang.UnsupportedOperationException
   :message "Unknown Collection type"
   :at [clojure.lang.Compiler$EmptyExpr emit "Compiler.java" 2929]}]
 [[clojure.lang.Compiler$EmptyExpr emit "Compiler.java" 2929]
  [clojure.lang.Compiler$BodyExpr emit "Compiler.java" 5905]
  [clojure.lang.Compiler$FnMethod doEmit "Compiler.java" 5453]
  [clojure.lang.Compiler$FnMethod emit "Compiler.java" 5311]
  [clojure.lang.Compiler$FnExpr emitMethods "Compiler.java" 3843]
  [clojure.lang.Compiler$ObjExpr compile "Compiler.java" 4489]
  [clojure.lang.Compiler$FnExpr parse "Compiler.java" 3983]
  [clojure.lang.Compiler analyzeSeq "Compiler.java" 6721]
  [clojure.lang.Compiler analyze "Compiler.java" 6524]
  [clojure.lang.Compiler eval "Compiler.java" 6779]
  [clojure.lang.Compiler eval "Compiler.java" 6745]
  [clojure.core$eval invoke "core.clj" 3081]
  ;; elided rest
user=> (eval `'~(map identity '(x)))

Cause: In the empty list case, the compiler here sees a LazySeq. I suspect something earlier in the stack should be producing an empty list instead, but haven't tracked it back yet.

Comment by Tim Engler [ 26/Apr/16 4:17 AM ]

Still exists in clojure 1.8

[CLJ-1918] Document await that it will never return if shutdown-agents was called Created: 25/Apr/16  Updated: 25/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Enhancement Priority: Trivial
Reporter: Ruslan Al-Fakikh Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: agents, docstring

Attachments: Text File CLJ-1918.patch    
Patch: Code
Approval: Prescreened


Undocumented behavior or the "await" function: it will never return if shutdown-agents was called.

This was a surprise to me to find yet another condition when await never returns.

(def my-agent (agent 0)) 

(defn sleep-and-inc [number] 
  (Thread/sleep 3000) 
  (println "action number" number "complete") 
  (inc number)) 

(println "sending off 2 times") 
(send-off my-agent sleep-and-inc) 
(send-off my-agent sleep-and-inc) 
(println "sending off complete") 

;making sure all the actions have completed to make it simple, 
;otherwise only the first action will be executed 
(Thread/sleep 7000) 


(println "starting await") 
(await my-agent) 
(println "await complete");this will never happen 

;here is how it behaves: 
;sending off 2 times 
;sending off complete 
;action number 0 complete 
;action number 1 complete 
;starting await 
;...hanging forever...

Proposal: Change the docstring for clojure.core/await from "...Will never return if a failed agent is restarted with :clear-actions true." to
"...Will never return if a failed agent is restarted with :clear-actions true or shutdown-agents was called."

Patch: CLJ-1918.patch

Prescreened by: Alex Miller

[CLJ-1917] internal-reduce extended on StringSeq calls `.length` on every iteration step Created: 24/Apr/16  Updated: 25/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Enhancement Priority: Minor
Reporter: Dimitrios Piliouras Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: performance


Approval: Triaged


internal-reduce extended on StringSeq calls `.length` (on the same String object) upon every iteration step [1]. There is absolutely no need for this as the length of a String cannot change. Therefore, it can be bound once (in the `let` a couple of lines up) and used thereafter.

[1]: https://github.com/clojure/clojure/blob/master/src/clj/clojure/core/protocols.clj#L151

[CLJ-1901] amap calls `alength` at every iteration step Created: 13/Mar/16  Updated: 24/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Enhancement Priority: Major
Reporter: Dimitrios Piliouras Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: arrays, performance


Attachments: Text File fix_amap.patch    
Patch: Code
Approval: Prescreened


During the 1.7 => 1.8 upgrade `areduce` was fixed to not call `alength` on the same thing, at every single iteration step. However, `amap` which suffers from the same issue was not fixed (even though exactly the same fix applies).


(def an-array (long-array 100000 0))
(dotimes [_ 50]
  (time (amap ^longs an-array idx ret (+ 1 (aget ^longs an-array idx)))))

Before (last time): 0.3930 ms
After (last time): 0.3459 ms

Patch: fix_amap.patch

Screened by: Alex Miller

Comment by Alex Miller [ 13/Mar/16 4:39 PM ]


Comment by Dimitrios Piliouras [ 24/Apr/16 1:33 PM ]

Not a problem. I actually noticed a very similar thing in the `internal-reduce` implementation for StringSeq [1]. The `.length()` method is called on the same String on every single iteration step, even though it is a constant. Is that easy enough to be sorted without me submitting another trivial patch? Thanks in advance...


Comment by Alex Miller [ 24/Apr/16 1:48 PM ]

Separate ticket would be preferred, thanks.

Comment by Dimitrios Piliouras [ 24/Apr/16 2:32 PM ]

Sure thing, I'll create it now.

[CLJ-1322] doseq with several bindings causes "ClassFormatError: Invalid Method Code length" Created: 10/Jan/14  Updated: 24/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.5
Fix Version/s: Release 1.9

Type: Defect Priority: Major
Reporter: Miikka Koskinen Assignee: Unassigned
Resolution: Unresolved Votes: 6
Labels: None

Clojure 1.5.1, java 1.7.0_25, OpenJDK Runtime Environment (IcedTea 2.3.10) (7u25-2.3.10-1ubuntu0.12.04.2)

Attachments: Text File doseq-bench.txt     Text File doseq.patch     File script.clj    
Patch: Code
Approval: Incomplete


Important Perf Note the new impl is faster for collections that are custom-reducible but not chunked, and is also faster for large numbers of bindings. The original implementation is hand tuned for chunked collections, and wins for larger chunked coll/smaller binding count scenarios, presumably due to the fn call/return tracking overhead of reduce. Details are in the comments.
Screened By
Patch doseq.patch

user=> (def a1 (range 10))
user=> (doseq [x1 a1 x2 a1 x3 a1 x4 a1 x5 a1 x6 a1 x7 a1 x8 a1] (do))
CompilerException java.lang.ClassFormatError: Invalid method Code length 69883 in class file user$eval1032, compiling:(NO_SOURCE_PATH:2:1)

While this example is silly, it's a problem we've hit a couple of times. It's pretty surprising when you have just a couple of lines of code and suddenly you get the code length error.

Comment by Kevin Downey [ 18/Apr/14 12:20 AM ]

reproduces with jdk 1.8.0 and clojure 1.6

Comment by Nicola Mometto [ 22/Apr/14 5:35 PM ]

A potential fix for this is to make doseq generate intermediate fns like `for` does instead of expanding all the code directly.

Comment by Ghadi Shayban [ 25/Jun/14 8:39 PM ]

Existing doseq handles chunked-traversal internally, deciding the
mechanics of traversal for a seq. In addition to possibly conflating
concerns, this is causing a code explosion blowup when more bindings are
added, approx 240 bytes of bytecode per binding (without modifiers).

This approach redefs doseq later in core.clj, after protocol-based
reduce (and other modern conveniences like destructuring.)

It supports the existing :let, :while, and :when modifiers.

New is a stronger assertion that modifiers cannot come before binding
expressions. (Same semantics as let, i.e. left to right)

valid: [x coll :when (foo x)]
invalid: [:when (foo x) x coll]

This implementation does not suffer from the code explosion problem.
About 25 bytes of bytecode + 1 fn per binding.

Implementing this without destructuring was not a party, luckily reduce
is defined later in core.

Comment by Andy Fingerhut [ 26/Jun/14 12:25 AM ]

For anyone reviewing this patch, note that there are already many tests for correct functionality of doseq in file test/clojure/test_clojure/for.clj. It may not be immediately obvious, but every test for 'for' defined with deftest-both is a test for 'for' and also for 'doseq'.

Regarding the current implementation of doseq: it in't simply that it is too many bytes per binding, it is that the code size doubles with each additional binding. See these results, which measures size of the macroexpanded form rather than byte code size, but those two things should be fairly linearly related to each other here:

(defn formsize [form]
  (count (with-out-str (print (macroexpand form)))))

user=> (formsize '(doseq [x (range 10)] (print x)))
user=> (formsize '(doseq [x (range 10) y (range 10)] (print x y)))
user=> (formsize '(doseq [x (range 10) y (range 10) z (range 10)] (print x y z)))
user=> (formsize '(doseq [x (range 10) y (range 10) z (range 10) w (range 10)] (print x y z w)))
user=> (formsize '(doseq [x (range 10) y (range 10) z (range 10) w (range 10) p (range 10)] (print x y z w p)))

Here are results for the same expressions after Ghadi's patch doseq.patch dated June 25 2014:

user=> (formsize '(doseq [x (range 10)] (print x)))
user=> (formsize '(doseq [x (range 10) y (range 10)] (print x y)))
user=> (formsize '(doseq [x (range 10) y (range 10) z (range 10)] (print x y z)))
user=> (formsize '(doseq [x (range 10) y (range 10) z (range 10) w (range 10)] (print x y z w)))
user=> (formsize '(doseq [x (range 10) y (range 10) z (range 10) w (range 10) p (range 10)] (print x y z w p)))

It would be good to see some performance results with and without this patch, too.

Comment by Stuart Halloway [ 28/Jun/14 2:21 PM ]

In the tests below, the new impl is called "doseq2", vs. the original impl "doseq"

(def hund (into [] (range 100)))
(def ten (into [] (range 10)))
(def arr (int-array 100))
(def s "superduper")

;; big seq, few bindings: doseq2 LOSES
(dotimes [_ 5]
  (time (doseq [a (range 100000000)])))
;; 1.2 sec

(dotimes [_ 5]
  (time (doseq2 [a (range 100000000)])))
;; 1.8 sec

;; small unchunked reducible, few bindings: doseq2 wins
(dotimes [_ 5]
  (time (doseq [a s b s c s])))
;; 0.5 sec

(dotimes [_ 5]
  (time (doseq2 [a s b s c s])))
;; 0.2 sec

(dotimes [_ 5]
  (time (doseq [a arr b arr c arr])))
;; 40 msec

(dotimes [_ 5]
  (time (doseq2 [a arr b arr c arr])))
;; 8 msec

;; small chunked reducible, few bindings: doseq2 LOSES
(dotimes [_ 5]
  (time (doseq [a hund b hund c hund])))
;; 2 msec

(dotimes [_ 5]
  (time (doseq2 [a hund b hund c hund])))
;; 8 msec

;; more bindings: doseq2 wins bigger and bigger
(dotimes [_ 5]
  (time (doseq [a ten b ten c ten d ten ])))
;; 2 msec

(dotimes [_ 5]
  (time (doseq2 [a ten b ten c ten d ten ])))
;; 0.4 msec

(dotimes [_ 5]
  (time (doseq [a ten b ten c ten d ten e ten])))
;; 18 msec

(dotimes [_ 5]
  (time (doseq2 [a ten b ten c ten d ten e ten])))
;; 1 msec
Comment by Ghadi Shayban [ 28/Jun/14 6:23 PM ]

Hmm, I cannot reproduce your results.

I'm not sure whether you are testing with lein, on what platform, what jvm opts.

Can we test using this little harness instead directly against clojure.jar? I've attached a the harness and two runs of results (one w/ default heap, the other 3GB w/ G1GC)

I added a medium and small (range) too.

Anecdotally, I see doseq2 outperform in all cases except the small range. Using criterium shows a wider performance gap favoring doseq2.

I pasted the results side by side for easier viewing.

core/doseq                          doseq2
"Elapsed time: 1610.865146 msecs"   "Elapsed time: 2315.427573 msecs"
"Elapsed time: 2561.079069 msecs"   "Elapsed time: 2232.479584 msecs"
"Elapsed time: 2446.674237 msecs"   "Elapsed time: 2234.556301 msecs"
"Elapsed time: 2443.129809 msecs"   "Elapsed time: 2224.302855 msecs"
"Elapsed time: 2456.406103 msecs"   "Elapsed time: 2210.383112 msecs"

;; med range, few bindings:
core/doseq                          doseq2
"Elapsed time: 28.383197 msecs"     "Elapsed time: 31.676448 msecs"
"Elapsed time: 13.908323 msecs"     "Elapsed time: 11.136818 msecs"
"Elapsed time: 18.956345 msecs"     "Elapsed time: 11.137122 msecs"
"Elapsed time: 12.367901 msecs"     "Elapsed time: 11.049121 msecs"
"Elapsed time: 13.449006 msecs"     "Elapsed time: 11.141385 msecs"

;; small range, few bindings:
core/doseq                          doseq2
"Elapsed time: 0.386334 msecs"      "Elapsed time: 0.372388 msecs"
"Elapsed time: 0.10521 msecs"       "Elapsed time: 0.203328 msecs"
"Elapsed time: 0.083378 msecs"      "Elapsed time: 0.179116 msecs"
"Elapsed time: 0.097281 msecs"      "Elapsed time: 0.150563 msecs"
"Elapsed time: 0.095649 msecs"      "Elapsed time: 0.167609 msecs"

;; small unchunked reducible, few bindings:
core/doseq                          doseq2
"Elapsed time: 2.351466 msecs"      "Elapsed time: 2.749858 msecs"
"Elapsed time: 0.755616 msecs"      "Elapsed time: 0.80578 msecs"
"Elapsed time: 0.664072 msecs"      "Elapsed time: 0.661074 msecs"
"Elapsed time: 0.549186 msecs"      "Elapsed time: 0.712239 msecs"
"Elapsed time: 0.551442 msecs"      "Elapsed time: 0.518207 msecs"

core/doseq                          doseq2
"Elapsed time: 95.237101 msecs"     "Elapsed time: 55.3067 msecs"
"Elapsed time: 41.030972 msecs"     "Elapsed time: 30.817747 msecs"
"Elapsed time: 42.107288 msecs"     "Elapsed time: 19.535747 msecs"
"Elapsed time: 41.088291 msecs"     "Elapsed time: 4.099174 msecs"
"Elapsed time: 41.03616 msecs"      "Elapsed time: 4.084832 msecs"

;; small chunked reducible, few bindings:
core/doseq                          doseq2
"Elapsed time: 31.793603 msecs"     "Elapsed time: 40.082492 msecs"
"Elapsed time: 17.302798 msecs"     "Elapsed time: 28.286991 msecs"
"Elapsed time: 17.212189 msecs"     "Elapsed time: 14.897374 msecs"
"Elapsed time: 17.266534 msecs"     "Elapsed time: 10.248547 msecs"
"Elapsed time: 17.227381 msecs"     "Elapsed time: 10.022326 msecs"

;; more bindings:
core/doseq                          doseq2
"Elapsed time: 4.418727 msecs"      "Elapsed time: 2.685198 msecs"
"Elapsed time: 2.421063 msecs"      "Elapsed time: 2.384134 msecs"
"Elapsed time: 2.210393 msecs"      "Elapsed time: 2.341696 msecs"
"Elapsed time: 2.450744 msecs"      "Elapsed time: 2.339638 msecs"
"Elapsed time: 2.223919 msecs"      "Elapsed time: 2.372942 msecs"

core/doseq                          doseq2
"Elapsed time: 28.869393 msecs"     "Elapsed time: 2.997713 msecs"
"Elapsed time: 22.414038 msecs"     "Elapsed time: 1.807955 msecs"
"Elapsed time: 21.913959 msecs"     "Elapsed time: 1.870567 msecs"
"Elapsed time: 22.357315 msecs"     "Elapsed time: 1.904163 msecs"
"Elapsed time: 21.138915 msecs"     "Elapsed time: 1.694175 msecs"
Comment by Ghadi Shayban [ 28/Jun/14 6:47 PM ]

It's good that the benchmarks contain empty doseq bodies in order to isolate the overhead of traversal. However, that represents 0% of actual real-world code.

At least for the first benchmark (large chunked seq), adding in some tiny amount of work did not change results signifantly. Neither for (map str [a])

(range 10000000) =>  (map str [a])
"Elapsed time: 586.822389 msecs"
"Elapsed time: 563.640203 msecs"
"Elapsed time: 369.922975 msecs"
"Elapsed time: 366.164601 msecs"
"Elapsed time: 373.27327 msecs"
"Elapsed time: 419.704021 msecs"
"Elapsed time: 371.065783 msecs"
"Elapsed time: 358.779231 msecs"
"Elapsed time: 363.874448 msecs"
"Elapsed time: 368.059586 msecs"

nor for intrisics like (inc a)

(range 10000000)
"Elapsed time: 317.091849 msecs"
"Elapsed time: 272.360988 msecs"
"Elapsed time: 215.501737 msecs"
"Elapsed time: 206.639181 msecs"
"Elapsed time: 206.883343 msecs"
"Elapsed time: 241.475974 msecs"
"Elapsed time: 193.154832 msecs"
"Elapsed time: 198.757873 msecs"
"Elapsed time: 197.803042 msecs"
"Elapsed time: 200.603786 msecs"

I still see reduce-based doseq ahead of the original, except for small seqs

Comment by Ghadi Shayban [ 04/Aug/14 2:55 PM ]

A form like the following will not work with this patch:

(go (doseq [c chs] (>! c :foo)))

as the go macro doesn't traverse fn boundaries. The only such code I know is core.async/mapcat*, a private fn supporting a fn that is marked deprecated.

Comment by Ghadi Shayban [ 07/Aug/14 2:09 PM ]

I see #'clojure.core/run! was just added, which has a similar limitation

Comment by Rich Hickey [ 29/Aug/14 8:19 AM ]

Please consider Ghadi's feedback, esp re: closures.

Comment by Ghadi Shayban [ 22/Sep/14 4:36 PM ]

The current expansion of a doseq [1] under a go form is less than ideal due to the amount of control flow. 14 states in the state machine vs. 7 with loop/recur

[1] Comparison of macroexpansion of (go ... doseq) vs (go ... loop/recur)

Comment by Nicola Mometto [ 25/Mar/15 6:07 PM ]

Related: CLJ-77

Comment by Nicola Mometto [ 03/Sep/15 12:59 PM ]

The general solution to this would be to automatically split methods when too large, using something like https://bitbucket.org/sperber/asm-method-size

Comment by Ghadi Shayban [ 24/Apr/16 12:25 AM ]

Example doseq impl and macroexpansion that does not suffer exponential bytecode growth. It also doesn't use any lambdas, so suitable for core.async.
It uses an explicit stack for the seqs/bindings.
It does not handle any chunking or modifiers yet.

[CLJ-1916] AOT compilation sometimes results in extra classes for already compiled namespaces Created: 19/Apr/16  Updated: 19/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Defect Priority: Minor
Reporter: Mike Kaplinskiy Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: aot


Case-in-point: clojure/tools.logging.


  • AOT compile all the namespaces in clojure/tools.logging (clojure.tools.logging & clojure.tools.logging.impl)
  • With the result on the classpath, AOT compile clojure/java.data (clojure.java.data)
  • Observe `clojure/tools/logging$eval32$fn__33.class` in the output of the second compile (make sure to have different output directories for the two compiles).

This is normally harmless, but becomes an issue if you try to cache AOT compilation output. When you try to cache previous AOT runs this way, you sometimes end up with two otherwise unrelated namespaces generating the same filename. If these had the same contents that would be fine, but there's no guarantee that they have the same contents (since 32 & 33 there are just (gensym)s). Depending on which one "wins" in a classpath this could end badly.

I'm not an expert here, but it would be nice if these "extras" were either generated as part of tools.logging or were somehow aliased into the namespace they were compiled from (e.g. clojure/java/data/$clojure$tools$logging$eval32$fn__33.class or clojure/tools/logging/$clojure$java$data$eval32$fn_33.class).

Comment by Kevin Downey [ 19/Apr/16 6:42 PM ]

tools.logging uses eval to generate some code only when certain classes are present on the classpath, eval generates class files, when you have aot compiling turned on, those class files will be output to the filesystem.

the reason the name is the way it is, is because the eval happens when the tools.logging namespace is loading, so the value of the ns var is the tools.logging namespace, which is what the compiler is generating the name from.

[CLJ-701] Primitive return type of loop and try is lost Created: 03/Jan/11  Updated: 19/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Backlog
Fix Version/s: Release 1.9

Type: Defect Priority: Major
Reporter: Chouser Assignee: Unassigned
Resolution: Unresolved Votes: 2
Labels: None

Clojure commit 9052ca1854b7b6202dba21fe2a45183a4534c501, version 1.3.0-master-SNAPSHOT

Attachments: Text File 0001-CLJ-701-add-HoistedMethod-to-the-compiler-for-hoisti.patch     Text File 0001-CLJ-701-add-HoistedMethod-to-the-compiler-for-hoisti-v2.patch     Text File 0002-CLJ-701-add-HoistedMethod-to-the-compiler-for-hoisti.patch     File hoistedmethod-pass-1.diff     File hoistedmethod-pass-2.diff     File hoistedmethod-pass-3.diff     File hoistedmethod-pass-4.diff     File hoistedmethod-pass-5.diff     File hoistedmethod-pass-6.diff     File hoistedmethod-pass-7.diff    
Patch: Code and Test
Approval: Incomplete

(set! *warn-on-reflection* true)
(fn [] (loop [b 0] (recur (loop [a 1] a))))

Generates the following warnings:

recur arg for primitive local: b is not matching primitive, had: Object, needed: long
Auto-boxing loop arg: b

This is interesting for several reasons. For one, if the arg to recur is a let form, there is no warning:

(fn [] (loop [b 0] (recur (let [a 1] a))))

Also, the compiler appears to understand the return type of loop forms just fine:

(use '[clojure.contrib.repl-utils :only [expression-info]])
(expression-info '(loop [a 1] a))
;=> {:class long, :primitive? true}

The problem can of course be worked around using an explicit cast on the loop form:

(fn [] (loop [b 0] (recur (long (loop [a 1] a)))))

Reported by leafw in IRC: http://clojure-log.n01se.net/date/2011-01-03.html#10:31

See Also: CLJ-1422

Patch: 0001-CLJ-701-add-HoistedMethod-to-the-compiler-for-hoisti-v2.patch

Comment by a_strange_guy [ 03/Jan/11 4:36 PM ]

The problem is that a 'loop form gets converted into an anonymous fn that gets called immediately, when the loop is in a expression context (eg. its return value is needed, but not as the return value of a method/fn).


(fn [] (loop [b 0] (recur (loop [a 1] a))))

gets converted into

(fn [] (loop [b 0] (recur ((fn [] (loop [a 1] a))))))

see the code in the compiler:

this conversion already bites you if you have mutable fields in a deftype and want to 'set! them in a loop


Comment by Christophe Grand [ 23/Nov/12 2:28 AM ]

loops in expression context are lifted into fns because else Hotspot doesn't optimize them.
This causes several problems:

  • type inference doesn't propagate outside of the loop[1]
  • the return value is never a primitive
  • mutable fields are inaccessible
  • surprise allocation of one closure objects each time the loop is entered.

Adressing all those problems isn't easy.
One can compute the type of the loop and emit a type hint but it works only with reference types. To make it works with primitive, primitie fns aren't enough since they return only long/double: you have to add explicit casts.
So solving the first two points can be done in a rather lccal way.
The two other points require more impacting changes, the goal would be to emit a method rather than a fn. So it means at the very least changing ObjExpr and adding a new subclassof ObjMethod.

[1] beware of CLJ-1111 when testing.

Comment by Alex Miller [ 21/Oct/13 10:28 PM ]

I don't think this is going to make it into 1.6, so removing the 1.6 tag.

Comment by Kevin Downey [ 21/Jul/14 7:14 PM ]

an immediate solution to this might be to hoist loops out in to distinct non-ifn types generated by the compiler with an invoke method that is typed to return the getJavaClass() type of the expression, that would give us the simplifying benefits of hoisting the code out and free use from the Object semantics of ifn

Comment by Kevin Downey [ 22/Jul/14 8:39 PM ]

I have attached a 3 part patch as hoistedmethod-pass-1.diff

3ed6fed8 adds a new ObjMethod type to represent expressions hoisted out in to their own methods on the enclosing class

9c39cac1 uses HoistedMethod to compile loops not in the return context

901e4505 hoists out try expressions and makes it possible for try to return a primitive expression (this might belong on http://dev.clojure.org/jira/browse/CLJ-1422)

Comment by Kevin Downey [ 22/Jul/14 8:54 PM ]

with hoistedmethod-pass-1.diff the example code generates bytecode like this

user=> (println (no.disassemble/disassemble (fn [] (loop [b 0] (recur (loop [a 1] a))))))
// Compiled from form-init1272682692522767658.clj (version 1.5 : 49.0, super bit)
public final class user$eval1675$fn__1676 extends clojure.lang.AFunction {
  // Field descriptor #7 Ljava/lang/Object;
  public static final java.lang.Object const__0;
  // Field descriptor #7 Ljava/lang/Object;
  public static final java.lang.Object const__1;
  // Method descriptor #10 ()V
  // Stack: 2, Locals: 0
  public static {};
     0  lconst_0
     1  invokestatic java.lang.Long.valueOf(long) : java.lang.Long [16]
     4  putstatic user$eval1675$fn__1676.const__0 : java.lang.Object [18]
     7  lconst_1
     8  invokestatic java.lang.Long.valueOf(long) : java.lang.Long [16]
    11  putstatic user$eval1675$fn__1676.const__1 : java.lang.Object [20]
    14  return
      Line numbers:
        [pc: 0, line: 1]

 // Method descriptor #10 ()V
  // Stack: 1, Locals: 1
  public user$eval1675$fn__1676();
    0  aload_0 [this]
    1  invokespecial clojure.lang.AFunction() [23]
    4  return
      Line numbers:
        [pc: 0, line: 1]
  // Method descriptor #25 ()Ljava/lang/Object;
  // Stack: 3, Locals: 3
  public java.lang.Object invoke();
     0  lconst_0
     1  lstore_1 [b]
     2  aload_0 [this]
     3  lload_1 [b]
     4  invokevirtual user$eval1675$fn__1676.__hoisted1677(long) : long [29]
     7  lstore_1 [b]
     8  goto 2
    11  areturn
      Line numbers:
        [pc: 0, line: 1]
      Local variable table:
        [pc: 2, pc: 11] local: b index: 1 type: long
        [pc: 0, pc: 11] local: this index: 0 type: java.lang.Object

 // Method descriptor #27 (J)J
  // Stack: 2, Locals: 5
  public long __hoisted1677(long b);
    0  lconst_1
    1  lstore_3 [a]
    2  lload_3
    3  lreturn
      Line numbers:
        [pc: 0, line: 1]
      Local variable table:
        [pc: 2, pc: 3] local: a index: 3 type: long
        [pc: 0, pc: 3] local: this index: 0 type: java.lang.Object
        [pc: 0, pc: 3] local: b index: 1 type: java.lang.Object


the body of the method __hoisted1677 is the inner loop

for reference the part of the bytecode from the same function compiled with 1.6.0 is pasted here https://gist.github.com/hiredman/f178a690718bde773ba0 the inner loop body is missing because it is implemented as its own IFn class that is instantiated and immediately executed. it closes over a boxed version of the numbers and returns an boxed version

Comment by Kevin Downey [ 23/Jul/14 12:43 AM ]

hoistedmethod-pass-2.diff replaces 901e4505 with f0a405e3 which fixes the implementation of MaybePrimitiveExpr for TryExpr

with hoistedmethod-pass-2.diff the largest clojure project I have quick access to (53kloc) compiles and all the tests pass

Comment by Alex Miller [ 23/Jul/14 12:03 PM ]

Thanks for the work on this!

Comment by Kevin Downey [ 23/Jul/14 2:05 PM ]

I have been working through running the tests for all the contribs projects with hoistedmethod-pass-2.diff, there are some bytecode verification errors compiling data.json and other errors elsewhere, so there is still work to do

Comment by Kevin Downey [ 25/Jul/14 7:08 PM ]


49782161 * add HoistedMethod to the compiler for hoisting expresssions out well typed methods
e60e6907 * hoist out loops if required
547ba069 * make TryExpr MaybePrimitive and hoist tries out as required

all contribs whose tests pass with master pass with this patch.

the change from hoistedmethod-pass-2.diff in this patch is the addition of some bookkeeping for arguments that take up more than one slot

Comment by Nicola Mometto [ 26/Jul/14 1:37 AM ]

Kevin there's still a bug regarding long/doubles handling:
On commit 49782161, line 101 of the diff, you're emitting gen.pop() if the expression is in STATEMENT position, you need to emit gen.pop2() instead if e.getReturnType is long.class or double.class

Test case:

user=> (fn [] (try 1 (finally)) 2)
VerifyError (class: user$eval1$fn__2, method: invoke signature: ()Ljava/lang/Object;) Attempt to split long or double on the stack  user/eval1 (NO_SOURCE_FILE:1)
Comment by Kevin Downey [ 26/Jul/14 1:46 AM ]

bah, all that work to figure out the thing I couldn't get right and of course I overlooked the thing I knew at the beginning. I want to get rid of some of the code duplication between emit and emitUnboxed for TryExpr, so when I get that done I'll fix the pop too

Comment by Kevin Downey [ 26/Jul/14 12:52 PM ]

hoistedmethod-pass-4.diff logically has the same three commits, but fixes the pop vs pop2 issue and rewrites emit and emitUnboxed for TryExpr to share most of their code

Comment by Kevin Downey [ 26/Jul/14 12:58 PM ]

hoistedmethod-pass-5.diff fixes a stupid mistake in the tests in hoistedmethod-pass-4.diff

Comment by Nicola Mometto [ 21/Aug/15 1:03 PM ]

Kevin Downey FWIW the patch no longer applies

Comment by Michael Blume [ 21/Aug/15 3:06 PM ]

A naive attempt to bring the patch up to date results in

     [java] Exception in thread "main" java.lang.ExceptionInInitializerError
     [java] 	at clojure.lang.Compile.<clinit>(Compile.java:29)
     [java] Caused by: java.lang.ClassCastException: clojure.lang.Compiler$HoistedMethod cannot be cast to clojure.lang.Compiler$FnMethod, compiling:(clojure/core.clj:439:11)
     [java] 	at clojure.lang.Compiler.analyzeSeq(Compiler.java:7360)
     [java] 	at clojure.lang.Compiler.analyze(Compiler.java:7154)
     [java] 	at clojure.lang.Compiler.analyzeSeq(Compiler.java:7341)
     [java] 	at clojure.lang.Compiler.analyze(Compiler.java:7154)
     [java] 	at clojure.lang.Compiler.access$300(Compiler.java:38)
     [java] 	at clojure.lang.Compiler$DefExpr$Parser.parse(Compiler.java:589)
     [java] 	at clojure.lang.Compiler.analyzeSeq(Compiler.java:7353)
     [java] 	at clojure.lang.Compiler.analyze(Compiler.java:7154)
     [java] 	at clojure.lang.Compiler.analyze(Compiler.java:7112)
     [java] 	at clojure.lang.Compiler.eval(Compiler.java:7416)
     [java] 	at clojure.lang.Compiler.load(Compiler.java:7859)
     [java] 	at clojure.lang.RT.loadResourceScript(RT.java:372)
     [java] 	at clojure.lang.RT.loadResourceScript(RT.java:363)
     [java] 	at clojure.lang.RT.load(RT.java:453)
     [java] 	at clojure.lang.RT.load(RT.java:419)
     [java] 	at clojure.lang.RT.doInit(RT.java:461)
     [java] 	at clojure.lang.RT.<clinit>(RT.java:331)
     [java] 	... 1 more
     [java] Caused by: java.lang.ClassCastException: clojure.lang.Compiler$HoistedMethod cannot be cast to clojure.lang.Compiler$FnMethod
     [java] 	at clojure.lang.Compiler$FnExpr.parse(Compiler.java:4466)
     [java] 	at clojure.lang.Compiler.analyzeSeq(Compiler.java:7351)
     [java] 	... 17 more
Comment by Kevin Downey [ 25/Aug/15 1:00 PM ]

the pass 6 patch builds cleanly on 1d5237f9d7db0bc5f6e929330108d016ac7bf76c(HEAD of master as of this moment) and runs clojure's tests. I have not verified it against other projects as I did with the previous patches (I don't remember how I did that)

Comment by Michael Blume [ 25/Aug/15 1:38 PM ]

I get the same error I shared before applying the new patch to 1d5237f

Comment by Alex Miller [ 25/Aug/15 1:56 PM ]

I get some whitespace warnings with hoistedmethod-pass-6.diff but the patch applies. On a compile I get:

     [java] Exception in thread "main" java.lang.ExceptionInInitializerError
     [java] 	at clojure.lang.Compile.<clinit>(Compile.java:29)
     [java] Caused by: java.lang.ClassCastException: clojure.lang.Compiler$HoistedMethod cannot be cast to clojure.lang.Compiler$FnMethod, compiling:(clojure/core.clj:439:11)
     [java] 	at clojure.lang.Compiler.analyzeSeq(Compiler.java:7362)
     [java] 	at clojure.lang.Compiler.analyze(Compiler.java:7156)
     [java] 	at clojure.lang.Compiler.analyzeSeq(Compiler.java:7343)
     [java] 	at clojure.lang.Compiler.analyze(Compiler.java:7156)
     [java] 	at clojure.lang.Compiler.access$300(Compiler.java:38)
     [java] 	at clojure.lang.Compiler$DefExpr$Parser.parse(Compiler.java:588)
     [java] 	at clojure.lang.Compiler.analyzeSeq(Compiler.java:7355)
     [java] 	at clojure.lang.Compiler.analyze(Compiler.java:7156)
     [java] 	at clojure.lang.Compiler.analyze(Compiler.java:7114)
     [java] 	at clojure.lang.Compiler.eval(Compiler.java:7418)
     [java] 	at clojure.lang.Compiler.load(Compiler.java:7861)
     [java] 	at clojure.lang.RT.loadResourceScript(RT.java:372)
     [java] 	at clojure.lang.RT.loadResourceScript(RT.java:363)
     [java] 	at clojure.lang.RT.load(RT.java:453)
     [java] 	at clojure.lang.RT.load(RT.java:419)
     [java] 	at clojure.lang.RT.doInit(RT.java:461)
     [java] 	at clojure.lang.RT.<clinit>(RT.java:331)
     [java] 	... 1 more
     [java] Caused by: java.lang.ClassCastException: clojure.lang.Compiler$HoistedMethod cannot be cast to clojure.lang.Compiler$FnMethod
     [java] 	at clojure.lang.Compiler$FnExpr.parse(Compiler.java:4468)
     [java] 	at clojure.lang.Compiler.analyzeSeq(Compiler.java:7353)
     [java] 	... 17 more
Comment by Nicola Mometto [ 25/Aug/15 2:36 PM ]

Looks like direct linking interacts with the diffs in this patch in non trivial ways.

Comment by Kevin Downey [ 25/Aug/15 3:05 PM ]

I must have screwed up running the tests some how, I definitely get the same error now

Comment by Kevin Downey [ 25/Aug/15 4:00 PM ]

after you get past the cast issuing (just adding some conditional logic there)

it looks like HoistedMethodInvocationExpr needs to be made aware of if it is emitting in an instance method or a static method, and do the right thing with regard to this pointers and argument offsets. this will likely require HoistedMethod growing the ability to be a static method (and maybe preferring static methods when possible).

if you cause HoistedMethod to set usesThis to true on methods that use it, then everything appears hunky-dory (if I ran the tests correctly), but this largely negates the new direct linking stuff, which is not good.

Comment by Kevin Downey [ 27/Aug/15 9:30 PM ]

hoistedmethod-pass-7.diff adds a single commit to hoistedmethod-pass-5.diff

the single commit changes hoisted methods to always be static methods, and adjusts the arguments in the invocation of the hoisted method based on if the containing function is a static/direct function or not.

again I haven't done the extended testing with this patch.

here is an example of what the hoisted methods look like

user> (println (disassemble (fn ^long [^long y] (let [x (try (/ 1 0) (catch Throwable t 0))] x))))                                                                       

// Compiled from form-init3851661302895745152.clj (version 1.5 : 49.0, super bit)                                                                                        
public final class user$eval1872$fn__1873 extends clojure.lang.AFunction implements clojure.lang.IFn$LL {                                                                
  // Field descriptor #9 Lclojure/lang/Var;                                                                                                                              
  public static final clojure.lang.Var const__0;                                                                                                                         
  // Field descriptor #11 Ljava/lang/Object;                                                                                                                             
  public static final java.lang.Object const__1;                                                                                                                         
  // Field descriptor #11 Ljava/lang/Object;                                                                                                                             
  public static final java.lang.Object const__2;                                                                                                                         
  // Method descriptor #14 ()V                                                                                                                                           
  // Stack: 2, Locals: 0                                                                                                                                                 
  public static {};                                                                                                                                                      
     0  ldc <String "clojure.core"> [16]                                                                                                                                 
     2  ldc <String "/"> [18]                                                                                                                                            
     4  invokestatic clojure.lang.RT.var(java.lang.String, java.lang.String) : clojure.lang.Var [24]                                                                     
     7  checkcast clojure.lang.Var [26]                                                                                                                                  
    10  putstatic user$eval1872$fn__1873.const__0 : clojure.lang.Var [28]                                                                                                
    13  lconst_1    
    14  invokestatic java.lang.Long.valueOf(long) : java.lang.Long [34]                                                                                                  
    17  putstatic user$eval1872$fn__1873.const__1 : java.lang.Object [36]                                                                                                
    20  lconst_0                                                                                                                                                         
    21  invokestatic java.lang.Long.valueOf(long) : java.lang.Long [34]                                                                                                  
    24  putstatic user$eval1872$fn__1873.const__2 : java.lang.Object [38]                                                                                                
    27  return                                                                                                                                                           
      Line numbers:                                                                                                                                                      
        [pc: 0, line: 1]                                                                                                                                                 
  // Method descriptor #14 ()V                                                                                                                                           
  // Stack: 1, Locals: 1                                                                                                                                                 
  public user$eval1872$fn__1873();                                                                                                                                       
    0  aload_0 [this]                                                                                                                                                    
    1  invokespecial clojure.lang.AFunction() [41]                                                                                                                       
    4  return                                                                                                                                                            
      Line numbers:                                                                                                                                                      
        [pc: 0, line: 1]                                                                                                                                                 
  // Method descriptor #43 (J)J                                                                                                                                          
  // Stack: 2, Locals: 4  
  public final long invokePrim(long y);                                                                                                                                  
     0  lload_1 [y]                                                                                                                                                      
     1  invokestatic user$eval1872$fn__1873.__hoisted1874(long) : java.lang.Object [47]                                                                                  
     4  astore_3 [x]                                                                                                                                                     
     5  aload_3 [x]                                                                                                                                                      
     6  aconst_null                                                                                                                                                      
     7  astore_3                                                                                                                                                         
     8  checkcast java.lang.Number [50]                                                                                                                                  
    11  invokevirtual java.lang.Number.longValue() : long [54]                                                                                                           
    14  lreturn                                                                                                                                                          
      Line numbers:                                                                                                                                                      
        [pc: 0, line: 1]                                                                                                                                                 
      Local variable table:                                                                                                                                              
        [pc: 5, pc: 8] local: x index: 3 type: java.lang.Object                                                                                                          
        [pc: 0, pc: 14] local: this index: 0 type: java.lang.Object                                                                                                      
        [pc: 0, pc: 14] local: y index: 1 type: long                                                                                                                     
  // Method descriptor #59 (Ljava/lang/Object;)Ljava/lang/Object;                                                                                                        
  // Stack: 5, Locals: 2                                                                                                                                                 
  public java.lang.Object invoke(java.lang.Object arg0);                                                                                                                 
     0  aload_0 [this]                                                                                                                                                   
     1  aload_1 [arg0]                                                                                                                                                   
     2  checkcast java.lang.Number [50]                                                                                                                                  
     5  invokestatic clojure.lang.RT.longCast(java.lang.Object) : long [63]                                                                                              
     8  invokeinterface clojure.lang.IFn$LL.invokePrim(long) : long [65] [nargs: 3]                                                                                      
    13  new java.lang.Long [30]                                                                                                                                          
    16  dup_x2                                                                                                                                                           
    17  dup_x2                                                                                                                                                           
    18  pop                                                                                                                                                              
    19  invokespecial java.lang.Long(long) [68]                                                                                                                          
    22  areturn                                                                                                                                                          
  // Method descriptor #45 (J)Ljava/lang/Object;                                                                                                                         
  // Stack: 4, Locals: 4                                                                                                                                                 
  public static java.lang.Object __hoisted1874(long arg0);                                                                                                               
     0  lconst_1                                                                                                                                                         
     1  lconst_0                                      
     2  invokestatic clojure.lang.Numbers.divide(long, long) : java.lang.Number [74]                                                                                     
     5  astore_2                                                                                                                                                         
     6  goto 17                                                                                                                                                          
     9  astore_3 [t]                                                                                                                                                     
    10  getstatic user$eval1872$fn__1873.const__2 : java.lang.Object [38]                                                                                                
    13  astore_2                                                                                                                                                         
    14  goto 17                                                                                                                                                          
    17  aload_2                                                                                                                                                          
    18  areturn                                                                                                                                                          
      Exception Table:                                                                                                                                                   
        [pc: 0, pc: 6] -> 9 when : java.lang.Throwable                                                                                                                   
      Line numbers:                                                                                                                                                      
        [pc: 0, line: 1]                                                                                                                                                 
        [pc: 2, line: 1]                                                                                                                                                 
      Local variable table:                                                                                                                                              
        [pc: 9, pc: 14] local: t index: 3 type: java.lang.Object                                                                                                         
        [pc: 0, pc: 18] local: y index: 1 type: java.lang.Object                                                                                                         

Comment by Kevin Downey [ 27/Aug/15 9:43 PM ]

there is still an issue with patch 7, (defn f [^long y] (let [x (try (+ 1 0) (catch Throwable t y))] x)) causes a verifier error

Comment by Nicola Mometto [ 28/Aug/15 11:41 AM ]

Patch 0001-CLJ-701-add-HoistedMethod-to-the-compiler-for-hoisti.patch is patch hoistedmethod-pass-7 with the following changes:

  • fixes the bug mentioned in the last comment by Kevin Downey
  • removes unnecessary whitespace and indentation changes
  • conforms indentation with the surrounding lines
  • squashes the commits into one as preferred by Rich

Authorship is maintained for Kevin Downey

Comment by Kevin Downey [ 28/Aug/15 5:40 PM ]

maybe we need a "Bronsa's Guide to Submitting Patches" to supplement http://dev.clojure.org/display/community/Developing+Patches, I had no idea a single commit was preferred, but that makes sense given the format, although I just noticed the bit on deleting old patches to avoid confusion. Is there a preferred format for patch names too?
If you have recommendations beyond patch formatting into the code itself I am all ears.

Comment by Nicola Mometto [ 28/Aug/15 6:08 PM ]

Kevin, having a single commit per patch is something that I've seen Rich and Alex ask for in a bunch of tickets, as I guess it makes it easier to evaluate the overall diff (even though it sacrifices granularity of description).
No idea for a preferred patch name, I find it hard to imagine it would matter – I just use whatever git format patch outputs.

One thing I personally prefer is to add the ticket name at the beginning of the commit message, it makes it easier to understand changes when using e.g. git blame

Comment by Andy Fingerhut [ 28/Aug/15 6:33 PM ]

Just now I added a suggestion to http://dev.clojure.org/display/community/Developing+Patches that one read their patches before attaching them, and remove any spurious white space changes. Also to consider submitting patches with a single commit, rather than ones broken up into multiple commits, as reviewers tend to prefer those.

Alex Miller recently edited that page with the note about putting the ticket id first in the commit comment.

Only preference on patch file names is the one on that page – that they end with '.patch' or '.diff', because Rich's preferred editor for reading them recognizes those suffixes and displays the file in a patch-specific mode, I would guess.

Comment by Nicola Mometto [ 28/Aug/15 6:38 PM ]

0001-CLJ-701-add-HoistedMethod-to-the-compiler-for-hoisti-v2.patch is the same as 0001-CLJ-701-add-HoistedMethod-to-the-compiler-for-hoisti.patch but it changes some indentation to avoid mixing tabs and spaces

Comment by Michael Blume [ 01/Sep/15 5:27 PM ]

I have a verify error on the latest patch, will attempt to provide a small test case:

Exception in thread "main" java.lang.VerifyError: (class: com/climate/scouting/homestead_test$fn__17125, method: invokeStatic signature: (Ljava/lang/Object;)Ljava/lang/Object Expecting to find integer on stack, compiling:(homestead_test.clj:43:3)

Comment by Michael Blume [ 01/Sep/15 6:29 PM ]


I'd rather remove the dependency on compojure-api but I'm having trouble reproducing without it

Comment by Michael Blume [ 01/Sep/15 8:01 PM ]

Ok, less stupid test case:

(let [^boolean foo true]
    (try foo
      (catch Throwable t))
Comment by Michael Blume [ 01/Sep/15 8:30 PM ]

...I wonder how hard it would be to write a generative test which produced small snippets of valid Clojure code, compiled them, and checked for errors. I bet we could've caught this.

Comment by Nicola Mometto [ 02/Sep/15 12:53 AM ]

Michael Blume I'm not sure this should be considered a compiler bug.
Contrary to numeric literals, boolean literals are never emitted unboxed and type hints are not casts so

(let [^boolean a true])
is lying to the compiler telling it a is an unboxed boolean when infact it is a boxed Boolean.

I'd say we wait for what Alex Miller or Rich Hickey think of this before considering Kevin Downey's current patch bugged, I personally (given the current compiler implementation) would consider this an user-code bug, currently ignored, that this patch merely exposes. IOW an instance of currently working code that is not however valid code

(I rest my case that if we had some better spec on what type-hints are supposed to be valid and some better compile-time validation on them, issues like this would not arise)

Comment by Nicola Mometto [ 02/Sep/15 1:13 AM ]

If this is considered a bug, the fix is trivial btw

@@ -5888,7 +5888,7 @@ public static class LocalBinding{
 	public boolean hasJavaClass() {
 		if(init != null && init.hasJavaClass()
-		   && Util.isPrimitive(init.getJavaClass())
+		   && (Util.isPrimitive(init.getJavaClass()) || Util.isPrimitive(tag))
 		   && !(init instanceof MaybePrimitiveExpr))
 			return false;
 		return tag != null
Comment by Kevin Downey [ 03/Sep/15 11:22 AM ]

I imagine ^boolean type hints (that don't do anything and are ignored) are going to become very common in clojure code, given everyone's keen interest in code sharing between clojure and clojurescript, and iirc clojurescript actually using ^boolean

Comment by Nicola Mometto [ 12/Sep/15 5:33 AM ]

Last patch doesn't compile anymore since it hits the bug reported in CLJ-1809

Comment by Alex Miller [ 18/Sep/15 8:28 AM ]

Moving to incomplete for now since it seems to be blocked on the other ticket

Comment by Kevin Downey [ 19/Jan/16 4:06 PM ]

0002-CLJ-701-add-HoistedMethod-to-the-compiler-for-hoisti.patch makes the change that Nicola suggested (with an extra null check). Michael's test case with the ^boolean type hint compiles now

Comment by Michael Blume [ 19/Jan/16 6:01 PM ]

Maybe this is out of scope for this ticket since it's just existing code that you're moving around, but I've always been confused by

//exception should be on stack
gen.visitVarInsn(OBJECT_TYPE.getOpcode(Opcodes.ISTORE), finallyLocal);
finallyExpr.emit(C.STATEMENT, objx, gen);
gen.visitVarInsn(OBJECT_TYPE.getOpcode(Opcodes.ILOAD), finallyLocal);

If we emit finallyExpr as C.STATEMENT, it should have no impact on the stack, and the exception should just be there without us needing to store and load it, right?

Comment by Michael Blume [ 19/Jan/16 6:02 PM ]

Also the latest patch seems to add a patch file to the root directory

Comment by Michael Blume [ 19/Jan/16 7:01 PM ]

New failing code

(defn foo [req]
  (let [^boolean b (get req :is-baz)]
Comment by Kevin Downey [ 20/Jan/16 12:05 AM ]

the latest patch applied to master is causing some test failures for data.xml

Testing clojure.data.xml.test-seq-tree

FAIL in (release-head-top) (test_seq_tree.clj:52)
expected: (= nil (.get input-ref))
  actual: (not (= nil (0 1 2 3 4 5 6 7 8 9)))

FAIL in (release-head-nested-late) (test_seq_tree.clj:60)
expected: (= nil (.get input-ref))
  actual: (not (= nil (1 2 :< 3 4 5 :>))
Comment by Nicola Mometto [ 20/Jan/16 5:54 AM ]

Michael Blume that's still an invalid type hint. Clojure is inconsistent all over the place with enforcing valid type hints, so even though I think we should handle the VerifyError explicitly, I don't think we need to care about making that code work.

WRT ^boolean type hints going to be common because clojurescript uses them – I don't think we should accept invalid code for the sake of interoparability. See CLJ-1883 for an instance of such a wrong type hint being used in Om, the solution was to fix Om, not to make the clojure compiler ignore yet another wrong type hint.

Comment by Kevin Downey [ 19/Apr/16 1:17 PM ]

I've just got around to trying to dig in to the data.xml failures I mentioned above.

Both those tests are related to head holding on a lazy seq. Both tests reliably fail with 0002-CLJ-701-add-HoistedMethod-to-the-compiler-for-hoisti.patch

So I suspect the hoisted method isn't properly clearing locals.

Comment by Kevin Downey [ 19/Apr/16 5:56 PM ]

so I don't forget, I realized the issue with data.xml is because the 'is' macro in the test expands in to a try/catch in an expression context, which is hoisted, and the hoist causes the whole environment not to be cleared until the hoisted method returns, which is obviously not correct.

[CLJ-1915] Tests for clojure.core/atom Created: 18/Apr/16  Updated: 18/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.9
Fix Version/s: None

Type: Enhancement Priority: Minor
Reporter: Linus Ericsson Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: atom

Attachments: File 0001-atom-unit-tests.clj    
Patch: Code and Test
Approval: Triaged


As per discussion with Alex Miller Mars 3rd 2016 on clojure-dev, Alex suggested we should add tests to clojure.core/atom functionality, of which there is none today.

I proposed tests for

  • the various ways to instatiate atoms (with and without validator and metadata)
  • that validators throws correctly
  • adding and removing watchers and that they trig as one would expected.
  • various ways of changing values (no aim for finding high-load concurrency issues or patological cases or similar).
  • that the arities of the interface in IAtom .swap works as expected - ie no reflection warnings (help/pointers for these type of cases needed!)
  • generative, tests trying to find the glitches while using atoms (the things excluded above).

Alex suggested generative testing, but no performance tests.

The patch "0001-atom-unit-tests.clj" (attached) contains unit tests for

  • creating "bare" atom
  • creating atom with validator
  • that validate-fn triggers and that the atom is unchanged
  • that deref (@) reader macro creates correct '(clojure.core/deref a)
  • that CAS works for ordinary values (no validator-triggering etc).

There are plenty of combinations not covered with these tests, but this is a start.

To cover all cases (like cas-ing with invalid values and other strange things) generative testing is indeed a must.

[CLJ-1905] loop should retain primitive int or float without widening Created: 29/Mar/16  Updated: 15/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Enhancement Priority: Minor
Reporter: Renzo Borgatti Assignee: Unassigned
Resolution: Unresolved Votes: 1
Labels: compiler, performance, primitives

Possibly older Clojure versions (but not verified).

Attachments: Text File 0001-CLJ-1905-remove-useless-widening-on-loop-bindings.patch    
Patch: Code and Test
Approval: Prescreened


In the following example:

(defn incrementer [n]
  (let [n (int n)]
    (loop [i (int 0)]
      (if (< i n)
        (recur (unchecked-inc-int i))

the loop-local starts as an int but is widened to a local but is widened to a long in the recur. It should be possible to retain the primitive int (or alternately float) type on the recur, rather than widening to long (or double).

The compiler code that is promoting the int seems to be:

Proposed: remove useless widening on loop bindings

Patch: 0001-CLJ-1905-remove-useless-widening-on-loop-bindings.patch

Prescreening comments: My main question here is: do we want to support primitive int/float loop vars?

Comment by Alex Miller [ 29/Mar/16 10:54 AM ]

I don't think anything but primitive longs or doubles are intended to be supported in loop/recur. Presuming that is correct, this would be the expected behavior.

The last major round of numeric/primitive refactoring made the decision to focus only on supporting primitive longs and doubles. One consequence of this is that primitive int loops are difficult to optimize - the main time I run into this is when working with Java interop in a tight loop on (for example) String, collection, or array operations (all of which are int-indexed).

Re unchecked-inc vs unchecked-inc-int, the primary reason to have these two variants is not performance but behavior. In particular, hashing operations often expect to get 32-bit int overflow semantics, not 64-bit int overflow semantics.

In summary, I think in the example given I would not write it with either int or unchecked-inc-int but with long and unchecked-inc if you are looking for best performance.

Comment by Nicola Mometto [ 29/Mar/16 11:01 AM ]

Alex Miller I don't think that's correct, as (AFAIK) it's only in fn params/returns that primitive types are supposed to be restricted to longs and doubles.
Note that for example, char, byte, boolean, short etc work just fine in both let and loop, while int and float work fine in let but not in loop.

This is caused by the following 4 lines in Compiler.java https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/Compiler.java#L6278-L6281

As far as I can tell, there's no reason for those 4 lines to be there at this point in time, and removing them makes int and float locals to be emitted correctly inside loops

This example in clojure.org itself seems to assume that ints should work in loops http://clojure.org/reference/java_interop#primitives

Also from that same paragraph:

All Java primitive types are supported
let/loop-bound locals can be of primitive types, having the inferred, possibly primitive type of their init-form

Comment by Alex Miller [ 29/Mar/16 12:07 PM ]

I agree that it should be possible to let-bound primitives of other types - I'm really talking about what happens on recur.

What would you expect to happen for a fn recur target? I wouldn't expect primitives other than long or double to work there since they can't occur in the function signature.

Note that I haven't closed this ticket, still talking through this.

Comment by Alex Miller [ 29/Mar/16 12:10 PM ]

I've definitely run into cases where creating a primitive int loop/recur would be useful for tight interop loops given how common int-indexing is in Java (some of the alioth benchmarks in particular would benefit from this). I think the argument is far weaker for float though.

Comment by Nicola Mometto [ 29/Mar/16 12:19 PM ]

I don't think we need to worry about fn recur targets at all, given that the only possible primitive bindings there are either long or double, and int/floats would get widened anyway, but good point, the tests in a patch for this ticket need to be sure that case is indeed handled.

RE: floats – I recall people complaining about bad support for floats when using clojure for graphical processing.

Even if admittedly a weak argument, I'm always of the idea that we should strike to be as consistent as possible. I don't think anybody would expect let/loop locals to behave differently, or differences between primitive types (other than the documented limitation about long/double being the only working prim types for fn arguments/return vals)

Comment by Alex Miller [ 29/Mar/16 12:30 PM ]

I'll leave this one in here but I'm going to treat it as an enhancement to current behavior. I think there's a good chance that Rich will just say this is working as intended.

I don't think the example is a very good one though and would welcome a better example. The reservations regarding unchecked-inc-int do not seem correct or valid to me (as usage should be fine on longs and is not designed for perf reasons anyways). A good example would should usage of a Java api in a loop where int-indexing and int-math gives better performance.

Comment by Nicola Mometto [ 30/Mar/16 8:51 AM ]

I edited the title as the bug is in `loop`, not `recur`

Comment by Nicola Mometto [ 02/Apr/16 9:55 AM ]

Attached a patch that removes the useless widenings done by the compiler on loop bindings, here's a benchmark demonstrating the speedup gained when areducing over int-arrays:

Before patch:

Clojure 1.8.0
user=> (use 'criterium.core)
user=> (let [xs (int-array (range 1e6))] (bench (areduce xs i ret 0 (+ ret (aget xs i)))))
Evaluation count : 64260 in 60 samples of 1071 calls.
             Execution time mean : 954.009929 µs
    Execution time std-deviation : 20.292809 µs
   Execution time lower quantile : 926.331747 µs ( 2.5%)
   Execution time upper quantile : 1.009189 ms (97.5%)
                   Overhead used : 1.840681 ns

Found 4 outliers in 60 samples (6.6667 %)
	low-severe	 4 (6.6667 %)
 Variance from outliers : 9.4244 % Variance is slightly inflated by outliers

After patch:

Clojure 1.9.0-master-SNAPSHOT
user=> (use 'criterium.core)
user=> (let [xs (int-array (range 1e6))] (bench (areduce xs i ret 0 (+ ret (aget xs i)))))
Evaluation count : 68640 in 60 samples of 1144 calls.
             Execution time mean : 870.462532 µs
    Execution time std-deviation : 13.100790 µs
   Execution time lower quantile : 852.357513 µs ( 2.5%)
   Execution time upper quantile : 896.531529 µs (97.5%)
                   Overhead used : 1.844045 ns

Found 1 outliers in 60 samples (1.6667 %)
	low-severe	 1 (1.6667 %)
 Variance from outliers : 1.6389 % Variance is slightly inflated by outliers

[CLJ-1908] Add clojure.test api to run single test with fixtures and report Created: 01/Apr/16  Updated: 15/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Enhancement Priority: Minor
Reporter: Howard Lewis Ship Assignee: Unassigned
Resolution: Unresolved Votes: 1
Labels: test

Attachments: Text File CLJ-1908-3.patch    
Patch: Code
Approval: Prescreened


When developing code, it is sometimes effective to focus on a single failing test, rather than running all tests in a namespace. This can be the case when running the tests takes some amount of time, or when running the tests produces a large volume of failures. The best option for running a single test with fixtures currently is `test-vars` ala:

(use 'clojure.test) 
(def counter (atom 0)) 
(defn setup [f] (swap! counter inc) (f)) ;; a :once fixture with state 
(use-fixtures :once setup) 
(deftest ex (println "counter =" @counter))

(test-vars [#'ex])  ;=> counter = 1 
(test-vars [#'ex])  ;=> counter = 2

However, this has the following issues:

  • No test reporting feedback such as you get with run-tests (on success, there is no output)
  • Need to specify var (not symbols) wrapped in a vector

Proposed: A new macro `run-test` that specifies a single symbol and does the same test reporting you get with `run-tests`. Usage:

(use 'clojure.test) 
(def counter (atom 0)) 
(defn setup [f] (swap! counter inc) (f)) ;; a :once fixture with state 
(use-fixtures :once setup) 
(deftest ex (println "counter =" @counter)) 

(run-test ex)

;=> Testing user
;=> counter = 1

;=> Ran 1 tests containing 0 assertions.
;=> 0 failures, 0 errors.
;=> {:test 1, :pass 0, :fail 0, :error 0, :type :summary}

(run-test ex)

;=> Testing user
;=> counter = 2

;=> Ran 1 tests containing 0 assertions.
;=> 0 failures, 0 errors.
;=> {:test 1, :pass 0, :fail 0, :error 0, :type :summary}

Patch: CLJ-1908-3.patch

Comment by Howard Lewis Ship [ 01/Apr/16 4:12 PM ]

Having trouble with the patch, in that, things that work at the REPL fail when executed via `mvn test`. Tracking down why is taking some time.

Comment by Howard Lewis Ship [ 01/Apr/16 4:40 PM ]

Initial patch; code works but mvn test fails and I haven't figured out why.

Comment by Howard Lewis Ship [ 01/Apr/16 5:44 PM ]

Thanks to Hiredman, was provided with insight that back ticks needed due to how Maven/Ant runs the tests. All tests now pass.

Comment by Alex Miller [ 01/Apr/16 6:43 PM ]

As far as I can tell, this is basically the same intent as CLJ-866 which was completed in Clojure 1.6. You can do this now with test-vars:

user=> (use 'clojure.test) 
user=> (def counter (atom 0)) 
user=> (defn setup [f] (swap! counter inc) (f)) ;; a :once fixture with state 
#'user/setup user=> (use-fixtures :once setup) {:clojure.test/once-fixtures (#object[user$setup 0x7106e68e "user$setup@7106e68e"])} user=> (deftest ex (println "counter =" @counter)) #'user/ex user=> (test-vars [#'ex]) 
counter = 1 
user=> (test-vars [#'ex]) 
counter = 2 
Comment by Howard Lewis Ship [ 03/Apr/16 12:27 PM ]

I think there is some advantage to being able to run the tests using is symbol, not its var. Further, the change I've suggested also returns the same kind of data that `run-tests` does.

Comment by Alex Miller [ 04/Apr/16 9:23 AM ]

Some changes needed on this patch before I will prescreen it:

  • Patch should be squashed to a single commit
  • Commit message in patch should start with "CLJ-1908"
  • Change run-test* to run-test-var
  • The docstring for run-test-var should be: "Run the test in Var v with fixtures and report." Kill the "called from" sentence".
  • The first sentence of the docstring for run-test should be: "Runs a single test in the current namespace." Remove "This is meant to be invoked interactively, from a REPL.". Last sentence is ok.
  • In run-test, replace (ns-resolve ns test-symbol) with the simpler (resolve test-symbol).
Comment by Howard Lewis Ship [ 04/Apr/16 10:52 AM ]

Thanks for the input; I'll have an updated patch shortly.

Comment by Howard Lewis Ship [ 08/Apr/16 2:51 PM ]

Updated patch, squashed and reflecting all of Alex's comments.

[CLJ-1914] Range realization has a race during concurrent execution Created: 14/Apr/16  Updated: 14/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.7, Release 1.8
Fix Version/s: None

Type: Defect Priority: Critical
Reporter: Ghadi Shayban Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: range

Attachments: Text File clj-1914-2.patch     Text File clj-1914-3.patch     Text File CLJ-1914.patch    
Patch: Code and Test
Approval: Prescreened


LongRange, which has some complex chunked seq caching, has a race in forceChunk.

chunkedMore, which calls forceChunk(), then checks for the existence of _chunkNext:

One thread calling forceChunk() can stop between these two lines:

While another thread thinks the first is done

Thanks to Kyle Kingsbury for the reproducing case https://gist.github.com/aphyr/8746181beeac6a728a3aa018804d56f6

Approach: Swap order of setting _chunk and _chunkNext so _chunk serves as a gate after both pieces of state have been set.

Patch: clj-1914-3.patch

Comment by Alex Miller [ 14/Apr/16 11:13 PM ]

It's not necessary to synchronize here - just swapping these two lines should address the race I think: https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/LongRange.java#L131-L132

Comment by Ghadi Shayban [ 14/Apr/16 11:22 PM ]

Good call. That's super subtle.

It appears all mutable assignment occurs in forceChunk() except for https://github.com/clojure/clojure/blob/master/src/jvm/clojure/lang/LongRange.java#L145 which should be OK (famous last words).

[CLJ-1913] core.reducers wrong documentation Created: 14/Apr/16  Updated: 14/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Defect Priority: Trivial
Reporter: Camilo Roca Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: docstring, reducers


Two issues regarding the documentation of core.reducers

  • There is a contradiction between the documentation mentioned in http://clojure.github.io/clojure/clojure.core-api.html#clojure.core.reducers/fold, with respect to the one mentioned here http://clojure.org/reference/reducers. Specifically on the line that states "(with a seed value obtained by calling (combinef) with no arguments)" on the former and "The reducef function will be called with no arguments to produce an identity value in each partition." on the later. Those two documentation references are contradictory. Either combinef is called with no arguments or reducef is called with no arguments.
  • The second doc issue is regarding the arities of most functions in core.reducers. With the introduction of transducers in Clojure 1.7. The single arity in functions like r/map or r/filter gives the impression that they return a transducer, whereas they just return a curried version of them. Nothing in the docstrings or the reference page mentions what is the return value of those functions with a single argument.

[CLJ-1912] Optimized version of the '<' and '>' functions for arties larger than 2 Created: 08/Apr/16  Updated: 08/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Enhancement Priority: Minor
Reporter: Anton Harald Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: performance


When looking at the code of the build-in functions '<' and '>', I was wondering, why (next more) is invoked twice in each comparison of two neighboring arguments.

Here is the original code of e.g. <

(defn <
  "Returns non-nil if nums are in monotonically increasing order,
  otherwise false."
  {:inline (fn [x y] `(. clojure.lang.Numbers (lt ~x ~y)))
   :inline-arities #{2}
   :added "1.0"}
  ([x] true)
  ([x y] (. clojure.lang.Numbers (lt x y)))
  ([x y & more]
   (if (< x y)
     (if (next more)
       (recur y (first more) (next more))
       (< y (first more)))

Here is a possible replacement for the n-arity part of the function:

([x y & more]
   (if (< x y)
     (if-let [n (next more)]
       (recur y (first more) n)
       (< y (first more)))

Now, (next more) would be computed only once per 'iteration'. On my machine, the modified version had 7% better performance. Of course, this only shows up when invoked with more than 2 arguments. e.g.: (apply < (range 100000...))

I'd be curious to hear, if there was a particular reason for taking this decision in the built-in function.

Comment by Alex Miller [ 08/Apr/16 4:23 PM ]

I don't think there is a particular reason, feel free to make a patch.

[CLJ-1817] Allow AssertionError messages for function :pre and :post conditions to be specified. Created: 23/Sep/15  Updated: 03/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Enhancement Priority: Major
Reporter: Tristan Strange Assignee: Colin Taylor
Resolution: Unresolved Votes: 5
Labels: error-reporting

All Clojure platforms

Attachments: Text File CLJ-1817.patch    
Patch: Code and Test
Approval: Triaged


A failing in a predicate in a list of :pre or :post conditions currently causes messages similar to one below to be displayed:

(defn must-be-a-map [m] {:pre [(map? m)]} m)
(must-be-a-map [])
;;=> AssertionError Assert failed: (map? m)  user/must-be-a-map (form-init.....clj:1)

These exception messages could be made significantly more descriptive by allowing specific messages strings to be associated with each predicate in :pre and :post conditions.

Predicate functions and there associated messages strings could be specified as a pair of values in a map:

(defn must-be-a-map 
  {:pre [{(map? m) "m must be a map due to some domain specific reason."}]}

The following would then produce an error message as follows:

(must-be-a-map 10)
AssertionError Assert failed: m must be a map due to some domain specific reason.
(map? m) user/must-be-a-map (form-init.....clj:1)

This would allow predicates without messages to specified alongside pairs of associated predicate message pairs as follows:

(defn n-and-m [n m] {:pre [(number? n) {(map? m) "You must provide a map!"}]})

This change would not break any existing functionality and still allow for predicates to be predefined elsewhere in code.

As a result pre and post conditions could provide a natural means of further documenting the ins and outs of a function, simplify the process of providing meaningful output when developing libraries and perhaps make the language better suited to teaching environments[1]

[1] http://wiki.science.ru.nl/tfpie/images/2/22/TFPIE2013_Steps_Towards_Teaching_Clojure.pdf

Comment by Colin Taylor [ 03/Apr/16 5:26 PM ]

Attached approach differs from that advocated for in the description by not requiring a map. The existing spec of :

{:pre [pre-expr*]
 :post [post-expr*]}

in effect becoming :

{:pre [(pre-expr assert-msg?)*]
 :post [(pre-expr assert-msg?)*]}

where assert-msg is a String. Note this means a (presumably erroneous) second String after an expression would be treated as a truthy pre-expr.

Contrived example :

(defn print-if-alphas-and-nums [arg] {:pre [(hasAlpha arg) "No alphas"
                                            (hasNum arg) "No numbers"
                                            (canPrint arg)]}
  (println arg))

user=> (print-if-alphas-and-nums "a5%")
user=> (print-if-alphas-and-nums "$$%")
AssertionError Assert failed: No alphas
(hasAlpha arg)  user/print-if-alphas-and-nums (NO_SOURCE_FILE:19)

I have considered extending the spec further to (pre-expr assert-msg? data-map)* perhaps supported by ex-info, ex-data analogues in assert-info, assert-data to convey diagnostic info (locals?). A map could contain a :msg key or perhaps the map is additional to the message string. I thought I'd wait for input though at this point.

I also considered allowing % substitution for the fn return value in the message as in :post conds, but how to escape?

Comment by Colin Taylor [ 03/Apr/16 6:17 PM ]

I should point out that the tests include the currently uncovered existing functionality too.

[CLJ-1243] Cannot resolve public generic method from package-private base class Created: 01/Aug/13  Updated: 03/Apr/16

Status: Open
Project: Clojure
Component/s: None
Affects Version/s: Release 1.3, Release 1.4, Release 1.5
Fix Version/s: None

Type: Defect Priority: Minor
Reporter: Stuart Sierra Assignee: Unassigned
Resolution: Unresolved Votes: 3
Labels: interop

Attachments: GZip Archive clj-1243-demo1.tar.gz    


The Clojure compiler cannot resolve a public generic method inherited from a package-private base class.

Instructions to reproduce:

  • In package P1
    • Define a package-private class A with generic type parameters
    • Define a public method M in A using generic types in either its arguments or return value
    • Define a public class B which extends A
  • In package P2
    • Construct an instance of B
    • Invoke B.M()

This is valid in Java. In Clojure, invoking B.M produces a reflection warning, followed by the error "java.lang.IllegalArgumentException: Can't call public method of non-public class." No amount of type-hinting prevents the warning or the error.

Attachment clj-1243-demo1.tar.gz contains sample code and script to demonstrate the problem.

Examples of Java projects which use public methods in package-private classes:

Comment by Stuart Sierra [ 01/Aug/13 5:11 PM ]

It is also not possible to call the method reflectively from Java.

This may be a bug in Java reflection: JDK-4283544

But why does it only happen on generic methods?

Comment by Stuart Sierra [ 08/Aug/13 11:59 AM ]

According to Rich Hickey, the presence of bridge methods is unspecified and inconsistent across JDK versions.

A possible solution is to use ASM to examine the bytecode of third-party Java classes, instead of the reflection API. That way the Clojure compiler would have access to the same information as the Java compiler.

Comment by Andy Fingerhut [ 17/Nov/13 11:01 PM ]

CLJ-1183 was closed as a duplicate of this one. Mentioning it here in case anyone working on this ticket wants to follow the link to it and read discussion or test cases described there.

Comment by Noam Ben Ari [ 21/Feb/15 4:55 AM ]

The current work around I use is to define a new Java class, add a static method that does what I need, and call that from Clojure.

Comment by Noam Ben Ari [ 21/Feb/15 9:28 AM ]

Also, I'm seeing this issue in 1.6 and 1.7(alpha5) but the issue mentions only up to 1.5 .

Comment by Adam Tait [ 03/Apr/16 5:32 PM ]

Just ran into this issue trying to use Google's Cloud APIs.
To use Google's Cloud Datastore, you need to access the .kind method on a protected generic subclass (BaseKey), to which KeyFactory extends.

Tested on both Clojure 1.7 & 1.8 at runtime, the following exception persists;

IllegalArgumentException Can't call public method of non-public class: public com.google.gcloud.datastore.BaseKey$Builder com.google.gcloud.datastore.BaseKey$Builder.kind(java.lang.String) clojure.lang.Reflector.invokeMatchingMethod (Reflector.java:88)

[CLJ-1909] Using thrown? in exceptions fails without doall Created: 02/Apr/16  Updated: 02/Apr/16  Resolved: 02/Apr/16

Status: Closed
Project: Clojure
Component/s: None
Affects Version/s: Release 1.8
Fix Version/s: None

Type: Defect Priority: Major
Reporter: Shriphani Palakodety Assignee: Unassigned
Resolution: Declined Votes: 0
Labels: None

OS: OS X and testing using lein test


I have added a small example in this repo: https://github.com/shriphani/thrown-test

See the test in https://github.com/shriphani/thrown-test/blob/master/test/thrown_test/core_test.clj

The first assertion fails, the second passes.

The output I get is: https://gist.github.com/shriphani/d9351d062f2f5c211879ef87c13277ac

Comment by Alex Miller [ 02/Apr/16 10:02 AM ]

In the example without doall, map will return a lazy seq that is not realized and thus you never encounter the exception. This is the expected behavior so I am declining the ticket.

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