In Clojure, it is generally the case that redefining something replaces the original, as opposed to augmenting it by merging the old and the new. This makes it easy to reason locally about how code works. One could argue that the following snippet has the same kind of issue you describe:

(defn foo [a] 1)
(defn foo [a b] 1)
(foo 1) ; is it a bug that the first arity is gone?

I also wonder whether the current behavior might be a convenience for some macros. (Clearly it wasn't for yours!) I am changing the type and title of the ticket to better reflect the nature of the request and see what the BDFL says.

Everything in this ticket needs to be said with more precision. I don't know what exactly the problem is nor what the proposed solution is.

One thing to note is that it is necessary to accept definitions under base interfaces, so the class areas are not strict, nor expected to be complete.

Stuart: The two foo forms you give are entirely separate, and to unify the two behaviors you would have to group them together. It's not at all unreasonable to suppose the user wants to define foo once, fiddle with it, and then redefine it - clojure.core does similar stuff with let, reduce, etc.

As written, deftype/reify have a somewhat similar "look" - because there is nothing physically grouping the declaration of Map with its functions, it's not clear what should happen when a heading like Map is given twice, and it's not specified in the docs.

I think the difference is that in the reify case, the two are in the same top-level form, so the compiler can detect that you're trying to do something "weird", so a silent redefinition (reasonable for your defn example) is surprising. There are a number of solutions that would reduce this surprise:

1) Permit or require reify to group things, as in (reify (Comparable (compare [this other] 1))). Then the explicit grouping of Comparable with its methods serves two purposes: it implies that other definitions for Comparable should be included in that grouping; and it makes it easier to do that, because you can just iterate over forms until you find Comparable, and then insert another definition.

2) Throw an exception if an interface is specified twice. This is not ideal because it can be a lot of work for the user to group things together themselves, while it's easy for deftype to do given the grouping it's already doing. However, it would avoid the confusion and surprise, by saying "that's not allowed" rather than leaving the user guessing what's gone wrong.

3) Interpret my original example code as an attempt to open the Map interface, add implementations, and then later add some more implementations.

I would have liked reify to implement (1) to begin with, but at this point I don't think the syntax is backwards-compatible, so it doesn't seem like a good idea. I suppose either (2) or (3) is fine, and they both seem like an improvement over the current confusing behavior. Of course, I prefer (3), but I can understand a desire to make reify reject syntax that is not immediately obvious in intent rather than interpreting it as what I think is the most useful intent.

Requires that patch on CLJ-782 be applied first.

Applies on master as of commit 66a88de9408e93cf2b0d73382e662624a54c6c86

still considering when to incorporate this

v2 of the patch applies to master as of commit eccde24c7fb63679f00c64b3c70c03956f0ce2c3

Patch clj-771-move-unchecked-casts-patch-v3.txt dated Sep 6 2012 is the same as Alexander Taggart's patch move-unchecked-casts.patch except that it has been updated to apply cleanly to latest Clojure master.

Patch clj-771-move-unchecked-casts-patch-v4.txt dated Oct 20 2012 is the same as Alexander Taggart's patch move-unchecked-casts.patch except that it has been updated to apply cleanly to latest Clojure master.

The patch clj-771-move-unchecked-casts-patch-v4.txt applies cleanly to latest master and passes all tests. Rich marked this ticket as Incomplete on Dec 9 2011 with the comment "still considering when to incorporate this" above. Is it reasonable to change it back to Vetted or Screened so it can be considered again, perhaps after Release 1.5 is made?

Patch clj-771-move-unchecked-casts-patch-v5.txt dated Feb 12 2013 is the same as Alexander Taggart's patch move-unchecked-casts.patch except that it has been updated to apply cleanly to latest Clojure master.

33.927 hiredman ,(binding [*print-dup* true] (pr-str (first {:a 1})))
33.928 clojurebot "#=(clojure.lang.MapEntry/create [:a 1])"
33.938 hiredman yeah, well, I was busy
33.941 chouser heh
33.949 hiredman ,(clojure.lang.MapEntry/create [:a 1])

The problem occurs in 1.2 but is fixed on master. Leaving in backlog in case we ever cut another 1.2 release--if not, then mark as fixed.

Converted from http://www.assembla.com/spaces/clojure/tickets/459

Converted from http://www.assembla.com/spaces/clojure/tickets/451

Converted from http://www.assembla.com/spaces/clojure/tickets/450

I independently wanted this. Here's a patch for: some, not-any?, every?, not-every?. If this is roughly what's wanted I'll be happy to add filter, remove, take-while, drop-while.

Note that there are a few cases of (every? identity ...) and (some identity ...) in core.clj itself; the patch removes "identity" from those.

clj-450-add-default-pred-arg-to-core-fns-patch.txt dated Apr 26 2012 is identical to Jason Orendorff's, except it is in git format. Jason is not on the list of Clojure contributors as of today. I have sent him an email asking if he has done so, or is planning to.

Of course I'd be happy to send in a contributor agreement. ...Is there actually any interest in taking this patch or something like it?

I don't know if there is any interest in taking this patch. Perhaps a Clojure screener will take a look at it and comment, but I am not a screener and can't promise anything.

Converted from http://www.assembla.com/spaces/clojure/tickets/440

Patch adds support for varargs. Builds on top of patch in CLJ-445.

Patch updated to current CLJ-445 patch.

Is this ticket on hold? I find myself typing (.someCall arg1 arg2 (into-array SomeType nil)) alot just to get the right method to be called. This ticket sounds like it would address that extraneous into-array arg that I use alot.

fixbug445.diff uploaded on Oct 29 2012 was written Oct 23 2010 by Alexander Taggart. I am simply copying it from the old Assembla ticket tracking system to here to make it more easily accessible. Not surprisingy, it doesn't apply cleanly to latest master. I don't know how much effort it would be to update it, but only a few hunks do not apply cleanly according to 'patch'. See the "Updating stale patches" section on the JIRA workflow page here: http://dev.clojure.org/display/design/JIRA+workflow

Ugh. Deleted the attachment because it was for CLJ-445, or at least it was named that way. CLJ-445 definitely has a long comment history, so if one or more of its patches address this issue, then you can read the discussion there to see the history.

I don't know of any "on hold" status for tickets, except for one or two where Rich Hickey has explicitly said in a comment that he wants to wait a while before making the change. There are just tickets that contributors choose to work on and ones that screeners choose to screen.

Converted from http://www.assembla.com/spaces/clojure/tickets/434

Converted from http://www.assembla.com/spaces/clojure/tickets/405

stu said: This could be fixed with an assert-valid-defrecord call in core_deftype, similar to assert-valid-fdecl in core.clj. Such a function would also be a place to hang other defrecord error messages.

Converted from http://www.assembla.com/spaces/clojure/tickets/401

Converted from http://www.assembla.com/spaces/clojure/tickets/400
Attachments:
flatten-enhancement.diff - https://www.assembla.com/spaces/clojure/documents/c5chtAJQir353NeJe5cbLr/download/c5chtAJQir353NeJe5cbLr

Converted from http://www.assembla.com/spaces/clojure/tickets/396

Converted from http://www.assembla.com/spaces/clojure/tickets/379
Attachments:
ticket-379-fix.diff - https://www.assembla.com/spaces/clojure/documents/c5XWHcD4yr34HveJe5ccaP/download/c5XWHcD4yr34HveJe5ccaP

alexott said: possible fix is attached

alexott said: [file:c5XWHcD4yr34HveJe5ccaP]

Converted from http://www.assembla.com/spaces/clojure/tickets/346
Attachments:
0347-pprint-update-2.diff - https://www.assembla.com/spaces/clojure/documents/diLxv6y4Sr35GVeJe5cbLr/download/diLxv6y4Sr35GVeJe5cbLr

stu said: [file:diLxv6y4Sr35GVeJe5cbLr]

stu said: The second patch includes the first, and adds another test.

tomfaulhaber said: This patch was attached to the wrong bug. It should be attached to bug #347. There is no fix for this bug yet.

Is this current?

Tom, this patch doesn't apply, and I am not sure why. Can you take a look?

Converted from http://www.assembla.com/spaces/clojure/tickets/319
Attachments:
TransactionalHashMap.java.patch - https://www.assembla.com/spaces/clojure/documents/cuuZnsuuWr36H0eJe5dVir/download/cuuZnsuuWr36H0eJe5dVir

megabyte2021 said: [file:cuuZnsuuWr36H0eJe5dVir]: The patch file

stu said: Please add a test case.

Converted from http://www.assembla.com/spaces/clojure/tickets/308

Added a CloseableResource protocol and extended it on java.io.Closeable (implemented by all Readers, Writers, Streams, Channels, Sockets). Use it in with-open.

All tests pass.

Seems to be related to Scopes (http://dev.clojure.org/jira/browse/CLJ-2).

Updated patch.

Patch 0001-Added-ClosableResource-protocol-for-with-open.patch dated 08/Mar/12 applies, builds, and tests cleanly on latest master as of Apr 2 2012. Tassilo has signed a CA.

Updated patch to apply cleanly against master again.

Converted from http://www.assembla.com/spaces/clojure/tickets/304

chouser@n01se.net said: That's a great question. get-source just needs a file name and line number.

If IMeta were a protocol, it could be extended to Class. That implementation could look for a "well-known" static field, perhaps? __clojure_meta or something? Then deftype would just have to populate that field, and get-source would be all set.

Does that plan have any merit? Is there a better place to store a file name and line number?

stu said: Seems like a reasonable idea, but this is going to get back-burnered for now, unless there is a dire use case we have missed.

Converted from http://www.assembla.com/spaces/clojure/tickets/277

bpsm said: I've attached a patch to #410, which also fixes this issue. (In fact, it turns out that it's the same patch tlj previously attached here.)

stu said: Duplicated association with ticket #410 was added

Converted from http://www.assembla.com/spaces/clojure/tickets/274

donmullen said: Updated each run to [_] for new syntax.

Now gives exception listed.

richhickey said: We're not going to allow closing over mutable fields. Instead we'll have to generate something other than fn for loops et al used as expressions. Not going to come before cinc

Converted from http://www.assembla.com/spaces/clojure/tickets/273

Converted from http://www.assembla.com/spaces/clojure/tickets/272

stu said: Suggestions from Volkan Yazici:

Hi,

I saw your "load/ns/require/use overhaul" ticket[1] and would like to
ask for a few extra overhaulings. I have a project called retop, and
here is its file hiearachy:

tr/edu/bilkent/cs/retop.clj
tr/edu/bilkent/cs/retop/km.clj
tr/edu/bilkent/cs/retop/graph.clj
tr/edu/bilkent/cs/retop/main.clj
tr/edu/bilkent/cs/retop/util.clj

In retop.clj, I have below ns definition.

(ns tr.edu.bilkent.cs.retop
(:gen-class)
(:import
(com.sun.jna
Function
Pointer)
(com.sun.jna.ptr
IntByReference)
(tr.edu.bilkent.cs.patoh
HyperGraph
HyperGraphException
Parititoning
ParititoningParameters))
(:load
"retop/util"
"retop/km"
"retop/graph"
"retop/main"))

And in every .clj file in retop/ directory I have below in-ns in the
very first line.

(in-ns 'tr.edu.bilkent.cs.retop)

The problems with the ns decleration are:

1) Most of the :import's in retop.clj only belong to a single .clj file.
For instance,

(tr.edu.bilkent.cs.patoh
HyperGraph
HyperGraphException
Parititoning
ParititoningParameters)

imports are only used by graph.clj. Yep, I can add an (import ...)
line just after the (in-ns ...), but wouldn't it be better if I can
specify that in (in-ns ...) form?

2) See (:load ...) clause in (ns ...) form. There are lots of
unnecessary directory prefixes. I'd be prefer something ala Common
Lisp's defpackage:

(:load
"packages" ; packages.clj
("retop"
"util" ; retop/util.clj
"km" ; retop/km.clj
"graph" ; retop/graph.clj
("graph"
"foo" ; retop/graph/foo.clj
"bar) ; retop/graph/bar.clj
"main")) ; retop/main.clj

Also, being able to use wildcards would be awesome.

3) There are inconsistencies between macros and functions. For instance,
consider:

(ns foo.bar.baz (:use mov))
(in-ns 'foo.bar.baz)
(use 'mov)

I'd like to get rid of quotations in both cases.

I'm not sure if I'm using the right tools and doing the right approach
for such a project. But if you agree with the above overhauling
requirements, I'd like to see them appear in the same assembla ticket as
well.

stuart.sierra said: My requests:

1. If writing macros that do not evaluate their arguments, provide function versions that do evaluate their arguments.

2. Do not support prefix lists for loading Clojure namespaces. It's hard to parse with external tools.

3. Do not conflate importing Java classes with loading Clojure namespaces. They are fundamentally different operations with different semantics.

I have implemented some ideas in a macro called "need" at http://github.com/stuartsierra/need

Further requests:

Permit tools to read the "ns" declaration and statically determine the dependencies of a namespace, without evaluating any code.

Permit tools to read the "ns" declaration and statically determine the dependencies of a namespace, without evaluating any code.

This would be great for building OSGi bundles where Bnd is currently not much help.

Converted from http://www.assembla.com/spaces/clojure/tickets/233

chouser@n01se.net said: Stuart, I don't see a patch attached.

Converted from http://www.assembla.com/spaces/clojure/tickets/213
Attachments:
invariants.patch - https://www.assembla.com/spaces/clojure/documents/dd4kUS3MWr3QvMeJe5aVNr/download/dd4kUS3MWr3QvMeJe5aVNr

Converted from http://www.assembla.com/spaces/clojure/tickets/200

hlship said: Trickier than I thought because cond is really wired into other fundamentals, like let.

cgrand said: Howard, what do you think of http://gist.github.com/432712 ?

Patch cond-let-clauses.diff on 23/Nov/12 adds inline :let clauses to cond, implementing CLJ-200. The code is based off of code by cgrand, with some tweaks so the implementation only relies on constructs defined earlier in core.clj, since when cond is defined, things aren't yet fully bootstrapped. Also added a test to control.clj.

Some comments: the docstring is missing, I believe you don't have to modify the original cond (except the docstring maybe), just redefine it later on once most of the language is defined – a bit like what is done for let for example.

There is still the unlikely eventuality that some code uses :let as :else. What about shipping a cond which complains on keywords (in test position) other than :else?

cond-let-clauses-with-docstring.diff contains the same patches as cond-let-clauses, but includes the original docstring for cond along with an additional sentence about the :let bindings.

Cgrand, I did see your example of redefining cond after most of the language is defined, but since I was able to figure out how to do it in the proper place, that makes the :let bindings available for users of cond downstream and avoids any unforeseen complications that might come from rebinding.

As for your other point, I think it is highly improbable that someone would have used :let in the :else position. However I can imagine someone intentionally using something like :true or :default. I think the idea of warning for other keywords is actually more likely to cause complications than the unlikely problem it is meant to solve.

I did resubmit the patch with the docstring restored. Thanks for pointing out that problem. I'm excited about this patch – I use :let bindings within the cond in my own code all the time. Thanks again for the blog post that started me on that path.

True, it's :unlikely for :let to happen.
However once :let is officially blessed, it may be better to provision for future other "special" keywords and thus to warn on "unsupported" keywords. Plus it will help out-of-order typists (like myself) to catch earlier a :elt instead of a :let
This is only my point of view. Thanks for trying to get :let in cond supported.

Mark, could you remove the obsolete earlier patch now that you have added the one with the doc string? Instructions for removing patches are under the heading "Removing Patches" on this page: http://dev.clojure.org/display/design/JIRA+workflow

Done.

I haven't figured out what is going wrong yet. I can apply the patch cond-let-clauses-with-docstring.diff to the latest Clojure master just fine. I can do "ant jar" and it will build a jar. When I do "ant", it fails with the new test for cond with :let, throwing a StackOverflowException. I can enter that same form into the REPL and it evaluates just as the test says it should. I can comment out that new test and all of the rest pass. But the new test doesn't pass when inside of the control.clj file. Anyone know why?

It's because of the brutal replacement performed by test/are: the placeholders for this are form are x and y but in Mark's test there are used as local names and are tries to substitute them recursively...
If one changes the local names to a and b for example it works.

cond-let-clauses-fixed-test.diff on 02/Dec/12 contains the same patch, but with the x,y locals in the test case changed to a,b so that it works properly in the are clause which uses x and y.

On Windows, I can't get Clojure's test suite task to work, either via ant or maven, which has made it difficult for me to verify the part of the patch that applies to the test suite works as expected; I had tested it as best I could in the REPL, using a version of Clojure built with the patch applied, but using this process, I missed the subtle interaction between are and the locals in the test case. Sorry about that. If someone can double-check that the test suite task now works with the newest patch, that would be great, and then I'll go ahead and remove the obsoleted patch. Thanks.

clj-200-cond-let-clauses-fixed-test-v2-patch.txt dated Dec 2 2012 is identical to Mark Engelberg's cond-let-clauses-fixed-test.diff of the same date, except it applies cleanly to the latest Clojure master.

I've verified that it compiles and passes all tests with latest Clojure master as of this date.

Mark, I've made sure to keep your name in the patch, since you wrote it. You should be able to remove your two attachments now, so the screener won't be confused which patch should be examined.

Mark, besides general issues with Windows not being used much (or maybe not at all?) by Clojure developers, there is the issue right now filed as CLJ-1076 that not all tests pass when run on Windows due to CR-LF line ending differences that cause several Clojure tests to fail, regardless of whether you use ant or maven to run them.

Converted from http://www.assembla.com/spaces/clojure/tickets/190
Attachments:
clojure-190-with-open.patch - https://www.assembla.com/spaces/clojure/documents/ca27R6Ojur3PQ0eJe5afGb/download/ca27R6Ojur3PQ0eJe5afGb

mikehinchey said: [file:ca27R6Ojur3PQ0eJe5afGb]: fix adds close method and tests

mikehinchey said: Note, I only defined methods for :default (reflection of .close) and Closeable, not sql or the numerous other classes in java that should be Closeable but are not. Maybe clojure.contrib.sql and other such libraries should define related close methods.

richhickey said: I want to hold off on this until scopes are in

Probably better implemented using a protocol. See http://dev.clojure.org/jira/browse/CLJ-308

Converted from http://www.assembla.com/spaces/clojure/tickets/153

Converted from http://www.assembla.com/spaces/clojure/tickets/150

Converted from http://www.assembla.com/spaces/clojure/tickets/148

scgilardi said: It's saying that the symbol com.howardlewisship.cascade.test-views/write already resolves to #���clojure.contrib.pprint/write, so you can't def a new write in com.howardlewisship.cascade.test-views.

What do you propose for an alternate wording of the error message here?

I think the issue is that only one side of the conflict is reported in the error, so if you get this kind of error in the middle of a large project it can be hard to figure out which namespace is conflicting. Take a toy example:

user=> (ns foo)
foo=> (def foobar 42)
foo=> (ns bar)
bar=> (def foobar 0)
bar=> (ns problem)
problem=> (refer 'foo)
problem=> (refer 'bar)
java.lang.IllegalStateException: foobar already refers to: #'foo/foobar in namespace: problem (NO_SOURCE_FILE:0)

In this case it would be best if the error said something like:

"Conflict referring to #'bar/foobar in #<Namespace problem> because foobar already refers to: #'foo/foobar."

This way the error message clearly identifies the location of the conflict, and the locations of the two conflicting vars.

Hopefully this helps clarify. I think I see where to fix it in warnOrFailOnReplace on line 88 of src/jvm/clojure/lang/Namespace.java, and this reminds me I need to send in a CA so I can pitch in next time...

It looks like the true conflict is in test-views, not in dom. A small example of the line number breakage showing the problem on master (1.3) would be very helpful.

Converted from http://www.assembla.com/spaces/clojure/tickets/140

Converted from http://www.assembla.com/spaces/clojure/tickets/130

richhickey said: Updating tickets (#127, #128, #129, #130)

juergenhoetzel said: This is still a issue on

Clojure 1.2.0-master-SNAPSHOT

Any progress, hints? I prefer interactive documentiation via slime/repl

Converted from http://www.assembla.com/spaces/clojure/tickets/129

richhickey said: Updating tickets (#127, #128, #129, #130)

Converted from http://www.assembla.com/spaces/clojure/tickets/126

richhickey said: Updating tickets (#8, #19, #30, #31, #126, #17, #42, #47, #50, #61, #64, #69, #71, #77, #79, #84, #87, #89, #96, #99, #103, #107, #112, #113, #114, #115, #118, #119, #121, #122, #124)

hiredman said: Related association with ticket #259 was added

Converted from http://www.assembla.com/spaces/clojure/tickets/115

richhickey said: Updating tickets (#8, #19, #30, #31, #126, #17, #42, #47, #50, #61, #64, #69, #71, #77, #79, #84, #87, #89, #96, #99, #103, #107, #112, #113, #114, #115, #118, #119, #121, #122, #124)

Converted from http://www.assembla.com/spaces/clojure/tickets/112

richhickey said: Updating tickets (#8, #19, #30, #31, #126, #17, #42, #47, #50, #61, #64, #69, #71, #77, #79, #84, #87, #89, #96, #99, #103, #107, #112, #113, #114, #115, #118, #119, #121, #122, #124)

Converted from http://www.assembla.com/spaces/clojure/tickets/107
Attachments:
bit-count.diff - https://www.assembla.com/spaces/clojure/documents/dqone2w4er3RbzeJe5afGb/download/dqone2w4er3RbzeJe5afGb

oranenj said: [file:dqone2w4er3RbzeJe5afGb]

richhickey said: Updating tickets (#8, #19, #30, #31, #126, #17, #42, #47, #50, #61, #64, #69, #71, #77, #79, #84, #87, #89, #96, #99, #103, #107, #112, #113, #114, #115, #118, #119, #121, #122, #124)

clj-107-add-bit-count-v1.txt is probably a correct updated version of the old patch linked above. Added a couple of unit tests.

Converted from http://www.assembla.com/spaces/clojure/tickets/99

richhickey said: Updating tickets (#8, #19, #30, #31, #126, #17, #42, #47, #50, #61, #64, #69, #71, #77, #79, #84, #87, #89, #96, #99, #103, #107, #112, #113, #114, #115, #118, #119, #121, #122, #124)

clj-99-min-key-max-key-performance-v1.txt dated Nov 15 2012 changes min-key and max-key to evaluate the function k on each of its other arguments at most once.

Converted from http://www.assembla.com/spaces/clojure/tickets/77

richhickey said: Updating tickets (#8, #19, #30, #31, #126, #17, #42, #47, #50, #61, #64, #69, #71, #77, #79, #84, #87, #89, #96, #99, #103, #107, #112, #113, #114, #115, #118, #119, #121, #122, #124)

Converted from http://www.assembla.com/spaces/clojure/tickets/64

richhickey said: Updating tickets (#8, #19, #30, #31, #126, #17, #42, #47, #50, #61, #64, #69, #71, #77, #79, #84, #87, #89, #96, #99, #103, #107, #112, #113, #114, #115, #118, #119, #121, #122, #124)

cemerick said: A patch has been submitted (via ticket #174) to add Serializable support to c.l.Keyword.

Converted from http://www.assembla.com/spaces/clojure/tickets/21

Converted from http://www.assembla.com/spaces/clojure/tickets/19

richhickey said: Updating tickets (#8, #19, #30, #31, #126, #17, #42, #47, #50, #61, #64, #69, #71, #77, #79, #84, #87, #89, #96, #99, #103, #107, #112, #113, #114, #115, #118, #119, #121, #122, #124)

this seems like a great task for someone just starting out contributing to clojure.

Converted from http://www.assembla.com/spaces/clojure/tickets/15

Wouldn't the naive approach incur realizing lazy sequences when adding them to a list or a vector or as values in a map?

Converted from http://www.assembla.com/spaces/clojure/tickets/5

Please see the attached patch which produces a (hopefully more clear) error message as shown below (given the broken code shown in the original bug report):

Clojure 1.4.0-master-SNAPSHOT
user=> (let [x 42 y 43] (+ x y))
85
user=> (let [[x y] {}] x)
UnsupportedOperationException left side of binding must be a symbol (found a PersistentVector instead).  clojure.lang.Compiler.checkLet (Compiler.java:6545)
user=>

In addition, this patch checks the argument of (let) as shown below:

user=> (let 42)
UnsupportedOperationException argument to (let)  must be a vector (found a Long instead).  clojure.lang.Compiler.checkLet (Compiler.java:6553)

Patch produced by doing git diff against commit ba930d95fc (master branch).

Sorry, this patch is wrong: it assumes that the left side of the binding is wrong - the [x y] in :

(let [[x y] {}] x)

because [x y] is a vector, when in fact, the left side is fine (per http://clojure.org/special_forms#let : "Clojure supports abstract structural binding, often called destructuring, in let binding lists".)

So it's the right side (the {}) that needs to be checked and flagged as erroneous, not the [x y].

Add patch better-error-for-let-vector-map-binding

This produces the following:

(let [[x y] {}] x)
Exception map binding to vector is not supported

There are other cases that are not handled by this though — like binding vector to a set

user=> (let [[x y] #{}] x)
UnsupportedOperationException nth not supported on this type: PersistentHashSet

Wondering if it might be better to try convert the map to a seq to support? Although this might be another issue.

Thoughts?

This seems too specific. Is this issue indicative of a larger problem that should be addressed? Even if this is the only case where bindings produce poor error messages, all the cases described above should be addressed in the patch.

Unfortunately, realized that this still does not cover the nested destructuring cases. Coming to the conclusion, that my approach above is not going to work for this.

File: clj-5-destructure-error.diff

Added support for nested destructuring errors

let [[[x1 y1][x2 y2]] [[1 2] {}]]
;=> UnsupportedOperationException let cannot destructure class clojure.lang.PersistentArrayMap.