Clojure

Output of clojure.reflect is not suitable for type hints

Details

  • Type: Defect Defect
  • Status: Open Open
  • Priority: Minor Minor
  • Resolution: Unresolved
  • Affects Version/s: Release 1.3
  • Fix Version/s: None
  • Component/s: None

Description

I'm trying to write a macro which generate reify forms using some reflection.

clojure.reflect produces type symbols similar to 'java.util.Iterator<>

Unfortunately, the compiler doesn't accept the <> syntax in type hints:

(reify Iterable (^{:tag java.util.Iterator} iterator [this] nil)) ; works

(reify Iterable (^{:tag java.util.Iterator<>} iterator [this] nil)) ;; fails
CompilerException java.lang.RuntimeException: java.lang.ClassNotFoundException: java.util.Iterator<>, compiling:(NO_SOURCE_PATH:1325)

It seems like the compiler should understand the <> just enough to strip it, rather than reject it. This would make it much easier to write correct macros involving type hinting and reflection.

The workaround I have been using is:

(defn hint
"clojure.reflect demarks generics with angle brackets, but
the compiler does not support generics in type hints"
[obj tag]
(let [tag (-> tag .toString (.replace "<>" "") symbol)]
(with-meta obj {:tag tag}))

Activity

Alex Miller made changes -
Field Original Value New Value
Labels reflection typehints

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Dates

  • Created:
    Updated: