Details
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Type:
Defect
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Status:
Open
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Priority:
Minor
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Resolution: Unresolved
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Affects Version/s: Release 1.4
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Fix Version/s: Release 1.6
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Component/s: None
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Labels:None
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Approval:Vetted
Description
Using clojure.walk functions fails surprisingly for data containing records defined with defrecord:
user=> (defrecord Foo [x])
user.Foo
user=> (def f (Foo. :x))
#'user/f
user=> (use 'clojure.walk)
nil
user=> (postwalk identity {:foo f})
UnsupportedOperationException Can't create empty: user.Foo user.Foo (NO_SOURCE_FILE:1)
This seems to be because clojure.walk/walk guards a call to (empty form) with a (coll? form) check. The check succeeds because records implement IPersistentCollection, but (empty form) throws an exception. This looks to me like a bug in clojure.walk (it should check records separately and either treat them as atomic or implement a way of walking through them) but perhaps it is a sign of some unclarity in the contract of collections.
maybe clojure should follow clojurescript's footsteps and move empty out of IPersistentCollection and create an
interface IEmptyableCollection extends IPersistentCollection { IEmptyableCollection empty(); }