On Mon, Dec 28, 2009 at 10:37 PM, Allen Rohner <aroh...@gmail.com> wrote:
> I tried to call merge on a deftype implementing IPersistentMap, and
> got an exception:
>
> user> (deftype Foo [a b] clojure.lang.IPersistentMap)
> #'user/Foo
>
> user> (Foo 1 2)
> #:Foo{:a 1, :b 2}
> user> (merge (Foo 1 2) {:a 3})
> ; Evaluation aborted.
>
> nth not supported on this type: PersistentArrayMap
> [Thrown class java.lang.UnsupportedOperationException]
>
> Restarts:
> 0: [ABORT] Return to SLIME's top level.
>
> Backtrace:
> 0: clojure.lang.RT.nth(RT.java:811)
> 1: user.Foo__15735.cons(NO_SOURCE_FILE:1)
> 2: clojure.lang.RT.conj(RT.java:534)
> 3: clojure.core$conj__3951.invoke(core.clj:67)
> 4: clojure.core$merge__4623$fn__4624.invoke(core.clj:1919)
> 5: clojure.core$reduce__4135.invoke(core.clj:665)
> 6: clojure.core$reduce__4135.invoke(core.clj:656)
> 7: clojure.core$merge__4623.doInvoke(core.clj:1919)
> 8: clojure.lang.RestFn.invoke(RestFn.java:422)
> 9: user$eval__15820.invoke(NO_SOURCE_FILE:1)
> 10: clojure.lang.Compiler.eval(Compiler.java:5258)
> 11: clojure.lang.Compiler.eval(Compiler.java:5226)
> 12: clojure.core$eval__4674.invoke(core.clj:2018)
> --more--
>
>
> Interestingly, drewr on IRC pointed out that
> (merge {:a 3} (Foo 1 2)) works. I then figured out that
> (merge {} (Foo 1 2) {:a 3}) works.
>
> This seems like a bug to me. Is it?
>
As we discussed in #clojure IRC, conj for deftypes does not yet
support all the flexibility of conj for e.g. hash-maps, in particular,
the conjing of another map. It does support vectors and map entries.
Rich
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