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[CLJ-1771] Support for multiple key(s)-value pairs in assoc-in Created: 29/Jun/15  Updated: 14/Jan/17

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

Type: Enhancement Priority: Major
Reporter: Griffin Smith Assignee: Unassigned
Resolution: Unresolved Votes: 9
Labels: None


Attachments: Text File clj-1771.patch    
Patch: Code and Test
Approval: Prescreened


It would be nice if assoc-in supported multiple key(s)-to-value pairs (and threw an error when there were an even number of arguments, just like assoc):

user=> (assoc-in {} [:a :b] 1 [:c :d] 2)
{:a {:b 1}, :c {:d 2}}
user=> (assoc-in {} [:a :b] 1 [:c :d])
IllegalArgumentException assoc-in expects even number of arguments after map/vector, found odd number

Patch: clj-1771.patch

Prescreened by: Alex Miller

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

Simple patch attached. I did not find any existing tests for assoc-in but I could add them if wanted.

Comment by Yehonathan Sharvit [ 19/Aug/16 10:19 AM ]

for the sake of symmetry with `assoc` I'd love to see this ticket fixed

Comment by Alex Miller [ 27/Nov/16 10:33 PM ]

Do you need the "if kvs" check?

Should have tests.

Comment by Matthew Gilliard [ 14/Jan/17 11:34 AM ]

Sorry for the delay - I don't get notifications from this JIRA for some reason.

The patch now includes tests.

Both `if` checks are necessary as we have 3 possible outcomes there:
1/ No more kvs (we are finished)
2/ More kvs (we need to recur)
3/ A sequence of keys but no value (throw IAE)

[CLJ-2099] Keywords with aliased namespaces cannot be read when the namespace is required in a reader conditional Created: 13/Jan/17  Updated: 13/Jan/17  Resolved: 13/Jan/17

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

Type: Defect Priority: Minor
Reporter: Viktor Magyari Assignee: Unassigned
Resolution: Declined Votes: 0
Labels: keywords, reader, readerconditionals


The title in itself isn't entirely true, but I couldn't find a way to describe it succintly (feel free to change).

The issue is easier to demonstrate with an example:

(ns foo
  #?(:cljs (:require [clojure.core :as c])))

#?(:cljs ::c/x)

When reading this in a :clj context, the reader cannot read ::c/x ("Invalid token: ::c/x"), despite the code being correct (presumably).
The same thing happens if the reader conditional branches are :clj and the source is read in a :cljs context.

Comment by Alex Miller [ 13/Jan/17 8:07 AM ]

This looks like expected behavior to me. Auto-resolved keywords rely on a resolution context and there isn't one at the point where ::c/x is being read.

Comment by Viktor Magyari [ 13/Jan/17 9:05 AM ]

To me it seems reasonable to expect the resolution context to include the clojure.core alias - more generally, include <platform> specific aliases in the <platform> branches of reader conditionals. Maybe consider this as an enhancement ticket?

Comment by Alex Miller [ 13/Jan/17 9:18 AM ]

To do this would require adding special handling specifically for ns or other things that create aliases, which implies conditional evaluation of some forms at read-time. You would also need some place (other than the current platform's namespace maps) to track other platform's namespace aliases. That's a lot of very special, custom stuff.

We're not going to add this.

[CLJ-2098] autodoc fails to load clojure/spec.clj Created: 12/Jan/17  Updated: 13/Jan/17

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

Type: Defect Priority: Critical
Reporter: Alex Miller Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: spec

Attachments: Text File clj-2098.patch    
Patch: Code
Approval: Vetted


Reported by Tom F for the autodoc process. The following (essentially) is what autodoc is doing that currently blows up:

tom@renoir:~/src/clj/autodoc-work-area/clojure/src$ java -cp clojure.jar clojure.main
Clojure 1.9.0-master-SNAPSHOT
user=> (load-file "src/clj/clojure/spec.clj")
CompilerException java.lang.IllegalArgumentException: No implementation of method: :conform* \
of protocol: #'clojure.spec/Spec found for class: clojure.spec$regex_spec_impl$reify__14279, \

Cause: There is code in Compiler.macroexpand() with the intention to suspend spec checking inside clojure.spec. However, it is currently doing an exact path match on SOURCE_PATH. In the load-file call above, this ends up being an absolute path.

Approach: Check for a path suffix rather than an exact match in Compiler.

Patch: clj-2098.patch

[CLJ-2089] Sorted colls with default comparator don't check that first element is Comparable Created: 19/Dec/16  Updated: 13/Jan/17

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

Type: Defect Priority: Major
Reporter: Alex Miller Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: collections

Attachments: Text File clj-2089.patch    
Patch: Code and Test
Approval: Vetted


Sorted maps and sets use the default comparator. The default comparator requires elements to be Comparable. PersistentTreeMap will not actually invoke the comparator until the second element is added to the map/set, so it is possible to create an invalid single element sorted map/set that will blow up only on later use.

The following examples create invalid "timebomb" collections that will throw ClassCastException if another element is added or if they're used in other ways (because sets are not comparable):

(sorted-set #{1})
(conj (sorted-set) #{1})
(sorted-map #{} 1)
(assoc (sorted-map) #{} 1)


(def s (sorted-set #{1}))  ;; this doesn't fail
(conj s #{2})              ;; first conj triggers error
ClassCastException clojure.lang.PersistentHashSet cannot be cast to java.lang.Comparable  clojure.lang.Util.compare (Util.java:153)

Cause: In PersistentTreeMap.add(), in the case where the existing tree is null, the comparator is never invoked and so the default comparator will never throw the ClassCastException seen on later compares. Note that none of this applies for a custom comparator (sorted-set-by and sorted-map-by) - those comparators can do whatever.

Proposed: In add(), if the map is empty AND the comparator is the default comparator, then check whether the added key is Comparable and throw CCE if not. Note that PersistentTreeMap is also the impl used by PersistentTreeSet so this covers both. The error message is customized to give you a better hint about the problem (and written to be applicable for both maps and sets). In the patch some existing (bad) tests had to be adjusted.

user=> (def s (sorted-set #{1}))
ClassCastException Default comparator requires nil, Number, or Comparable: #{1}  clojure.lang.PersistentTreeMap.add (PersistentTreeMap.java:335)

One downside of the current patch is that does not catch the equivalent problem if using a custom comparator and a bad first element. You could maybe do this by calling comp.compare(k,k) (although many comparators, like the default comparator, have an early identity check that would not fail on this). For now, decided that if you supply a custom comparator, it's up to you to not use it with elements that don't work with that comparator.

Patch: clj-2089.patch

[CLJ-1368] Document usage for case with non-readable constants Created: 02/Mar/14  Updated: 13/Jan/17

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

Type: Enhancement Priority: Minor
Reporter: Herwig Hochleitner Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: docs, interop



It is pretty obscure how to get constant-time dispatch for e.g. Enums, even if user knows about case.


The possibility to dispatch to arbitrary constants with case, by wrapper macro, should be documented.


  • Should it warn against doing that with unstable values?
  • Should it mention anything else than java Enums?

Case Techniques

Case is documented for accepting all readable forms as test-constants. However, it can also be made to use any compile-time-known constants as test-constants, by wrapping it in another macro.

Sometimes this is appropriate, e.g. when dispatching on a java Enum.
Other times, less so, e.g. when dispatching on objects whose hash changes when the vm is restarted (breaks AOT).


This technique is an application of a more general technique: Passing non-literals to a macro from another macro.
Are there other macros that have use cases like this?



Comment by Herwig Hochleitner [ 02/Mar/14 11:25 AM ]

This is a duplicate of http://dev.clojure.org/jira/browse/CLJ-1367

Actually, it's an alternate solution

Comment by Petr Gladkikh [ 13/Jan/17 5:58 AM ]

Probably this ticket and CLJ-1367 linger for so long because there's already 'condp' that can be used as follows:

(condp = test-value
  JavaClass/CONST1 result1
  JavaClass/CONST2 result2)

This is sequential and slower but is about as concise as plain case.

However if this is the form to be used instead of plain 'case' this should be suggested by documentation.

[CLJ-2097] Improve generation failure exception Created: 10/Jan/17  Updated: 11/Jan/17

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

Type: Enhancement Priority: Major
Reporter: Russell Mull Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: generator, spec


It's pretty easy to write a spec whose generator fails like this:

Couldn't satisfy such-that predicate after 100 tries.

This is of course expected in many ways, but it's a very unhelpful error. Some things that could make this better include:

  • Including the spec that failed in the exception. I only see one invocation of gen/such-that in spec.clj, and it appears to have the spec's form at hand. gen/such-that takes an exception constructor where this could be used.
  • Allow max-tries to be changed from the hardcoded value of 100. When dealing with an intermittent failure, it can be useful to crank down max-tries to a very small number, making the failure easier to reproduce.

Comment by Alex Miller [ 11/Jan/17 8:41 AM ]

These are reasonable suggestions and this area is likely to evolve in tandem with test.check to provide better info.

[CLJ-2074] ::keys spec conflicts with destructuring spec Created: 02/Dec/16  Updated: 11/Jan/17

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

Type: Defect Priority: Major
Reporter: Nicola Mometto Assignee: Alex Miller
Resolution: Unresolved Votes: 1
Labels: destructuring, spec

Attachments: File close-destructuring-keys-specs.diff    
Patch: Code


As a consequence of the destructuring specs being implemented in terms of `s/keys`, defining a spec for `::keys` or `::strs` is problematic at the moment, because it will conflict with trying to use `::keys` for destructuring:

user=> (require '[clojure.spec :as s])
user=> (s/def ::keys nil?)
user=> (let [{::keys [a]} {::a 1}] a)
ExceptionInfo Call to clojure.core/let did not conform to spec:
In: [0 0] val: #:user{:keys [a]} fails spec: :clojure.core.specs/local-name at: [:args :bindings :binding :sym] predicate: simple-symbol?
In: [0 0 0] val: ([:user/keys [a]]) fails spec: :clojure.core.specs/seq-binding-form at: [:args :bindings :binding :seq] predicate: (cat :elems (* :clojure.core.specs/binding-form) :rest (? (cat :amp #{(quote &)} :form :clojure.core.specs/binding-form)) :as (? (cat :as #{:as} :sym :clojure.core.specs/local-name))),  Extra input
In: [0 0 :user/keys] val: [a] fails spec: :user/keys at: [:args :bindings :binding :map :user/keys] predicate: nil?
:clojure.spec/args  ([#:user{:keys [a]} #:user{:a 1}] a)
  clojure.core/ex-info (core.clj:4725)

This feels like an implementation detail leak.

Comment by Brandon Bloom [ 10/Jan/17 5:36 PM ]

I also just ran in to this problem. Just wanted to say that I'd like to see a fix, but I'm not quite sure about the proposed solution. Or, at least, the name "closed?" seems to imply a non-extensible map, when in reality the flag more or less means "not a map that participates in the global keys system", for which I do not have a better name suggestion.

Comment by Alex Miller [ 11/Jan/17 8:35 AM ]

The proposed patch is a non-starter. I have some ideas on how to address this, but just haven't gotten around to working on it yet.

Comment by Alex Miller [ 11/Jan/17 8:37 AM ]

Removed proposal and patch from the ticket as we will not be going this direction. Captured here for reference:

"The attached patch implements a proposed solution to this issue, by adding a `:closed?` option to `s/keys` and using it for the destructuring spec. If `s/keys` is used with `:closed?` set to true, `conform` will only validate declared specs as opposed to the default behaviour of `s/keys` of validating all namespaced keywords with existing specs.

After this patch, the above example runs fine and usages of `s/keys` without `:closed?` set to true will validate against `::keys` as per current behaviour.

Patch: close-destructuring-keys-specs.diff"

[CLJ-2091] clojure.lang.APersistentVector#hashCode is not thread-safe Created: 24/Dec/16  Updated: 10/Jan/17

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

Type: Defect Priority: Major
Reporter: thurston n Assignee: Unassigned
Resolution: Unresolved Votes: 0
Labels: collections, concurrency

Attachments: File clj-2091-0.diff     File clj-2091-default-initialization.diff    
Patch: Code
Approval: Prescreened


Problem: clojure.lang.APersistentVector#hashCode contain a deliberate data race on hash computation. However, the code as written does not follow safe practices for the intended data race. Specifically, the problem arises because the hashCode() (and hasheq()) method make multiple reads of the (unsynchronized) _hash field. The JMM permits these reads to return different values. Specifically, the last read in the return may return the pre-computed value -1, which is not the desired hash value. This problem also applies to APersistentMap, APersistentSet, and PersistentQueue.

See: http://jeremymanson.blogspot.com/2008/12/benign-data-races-in-java.html for a good description of the problem.

Fix: The main fix is to read the cached hash field only once and return the value of the local computation, not the value of the field.

A secondary change that is also beneficial is to use the default initializer value (which has special ordering in the JMM to the beginning of the thread) rather than setting and using -1 as the sentinel value.

In both cases these changes follow the canonical idioms used in java.lang.String for lazy hash computation. The patch covers both.

Patch: clj-2091-default-initialization.diff - note that this patch will indicate whitespace errors when applied due to the wacky line endings in PersistentQueue. The problem here is really the PQ formatting, not the patch.

Prescreened by: Alex Miller

There are some hash-related tests already but I also spot-checked that hash computations are returning the same value with and without the patch for the collections in question.

Comment by thurston n [ 24/Dec/16 4:38 PM ]

I can of course provide a patch, but as this is my first issue and am generally unfamiliar with clojure's practices and because this issue is not restricted to APersistentVector#hashCode, I thought it best to hold off and let the stewards decide how to proceed and how I could best help

Comment by Alex Miller [ 31/Dec/16 12:47 PM ]

Patch welcome (but please sign the contributor's agreement first - http://clojure.org/community/contributing). Also, see the processes for developing patches at http://dev.clojure.org/display/community/Developing+Patches.

AFAICT, the affected classes are APersistentVector, APersistentMap, APersistentSet, and PersistentQueue? Would be ok by me to cover all of them in a single patch.

Comment by thurston n [ 03/Jan/17 4:00 PM ]

AFAICT, the affected classes are APersistentVector, APersistentMap, APersistentSet, and PersistentQueue?

  • Dunno. However my experience tells me that the broken idiom (racy cache/memoization) is likely elsewhere; but I know of no systematic way of finding them. Regardless, I'll just focus on those 4 classes.
  • My plan is to also fix #hasheq(). It's the same problem; if you don't want that then just let me know and I'll refrain.
  • I'm not planning to deal with the initialization of #_hash and #_hasheq (currently inline-initialized to -1); that's a separate (although related) thread-safety problem. Might they be just what we refer to as a "legacy idiosyncrasy"? If so, then they really should be changed to just be default-initialized. I did, as an experiment, change one to default initialization, and the tests passed - that should be enough, but given that the persistent classes are serializable, code-coverage, et al., I can't say for sure. So I'll leave it to others more familiar with the codebase to make that determination. I note that if it is in future determined to change them, then #hashCode() and #hasheq() will need to be modified (trivially) accordingly.

That's the plan. Sound good?

Comment by Alex Miller [ 03/Jan/17 9:49 PM ]

I thought the non-default initialization was part of what you were describing, so now I'm not sure we're on the same page. Maybe you can just patch one so we have something concrete to talk about.

Comment by thurston n [ 03/Jan/17 9:56 PM ]

I'm not sure what you mean by "patch one" - I just submitted a patch, did you look at that?

Comment by Alex Miller [ 03/Jan/17 10:13 PM ]

I meant one class - sorry, I didn't see the patch. I will look at it tomorrow with fresh eyes.

Comment by thurston n [ 03/Jan/17 11:02 PM ]


To be clear, as I mentioned in today's earlier comment, I would advise removing the inline-initialization, viz.

int _hash = -1;
int _hasheq = -1;


int _hash;
int _hasheq;

As I wrote, the extant tests would pass (of course, changing #hashCode() and #hasheq() appropriately)

But the initialization issue is a different, although certainly not orthogonal, issue than the one my patch addresses.

Currently, (i.e. pre-patch), #hashCode() can return a spurious -1 even if an APersistentVector instance is safely published - my patch fixes that.

However, because of the inline-initialization, an APersistentVector instance that is not safely published could return a spurious 0 from #hashCode(), even with my patch.

Now if the inline-initialization is just a "legacy idiosyncrasy" (and we all do that at one time or another), then it could be safely replaced (along with the appropriate modification to my patch) and all APersistentVector instances (safely published or not), would have #hashCode() implementations that are correct.

Comment by Alex Miller [ 06/Jan/17 3:19 PM ]

Ok, I went over all this again and it makes sense to me. I think you should proceed and also make the initializer change (remove the -1 as sentinel and replace with no initializer and 0 for the comparison checks in the methods).

Comment by thurston n [ 06/Jan/17 11:36 PM ]

Combines the 2 commits into a single commit patch
So incorporates the original patch changes (single read) with default initialization and checks for zero
Don't know what to do with PersistentQueue's mixed line-endings – that I'll leave to you to deal with

Comment by thurston n [ 09/Jan/17 8:16 PM ]

Problem also in core.lang.ASeq#hashCode() and core.lang.ASeq#hasheq() - although thankfully without inline initialization

Surely not the last place either

Comment by Alex Miller [ 10/Jan/17 8:33 AM ]

Feel free to update the patch if you like

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