Details
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Type:
Improvement
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Status: Closed
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Priority:
Major
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Resolution: Completed
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Affects versions: None
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Fix versions: Release 1.7
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Approval:Ok
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Patch:Code and Test
Description
Example showing how a local fn can be hinted but an anonymous function cannot:
;; OK
user> (let [ex (java.util.concurrent.Executors/newFixedThreadPool 1)
f (fn [])]
(.submit ex ^Runnable f))
nil
;; ERROR - this should work the same as the previous
user> (let [ex (java.util.concurrent.Executors/newFixedThreadPool 1)]
(.submit ex #()))
CompilerException java.lang.IllegalArgumentException: More than one matching method found: submit, compiling:(/private/var/folders/7r/_1fj0f517rgcxwx79mn79mfc0000gn/T/form-init7901279404687292754.clj:3:9)
Cause: Functions have metadata, but Compiler does not look in them for type hints. Var expressions and local bindings use :tag metadata to override return of getJavaClass(). Compiler parses #() into a FnExpr, which always return AFunction as its class.
Proposed: Change FnExpr.getJavaClass() to return tag as type if it is available.
Patch: clj-1378-v2.diff
Screened by: Alex Miller
