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  • #3545

Closed
Open
Opened Sep 27, 2009 by LouisWasserman@trac-LouisWasserman

As-patterns for type signatures

The proposal: in any type signature, the presence of type variable

x@pat

matches the type specified by pat, and replaces any occurrences of the type variable x with pat. In particular, this might be comparable to defining

type x (free variables in pat) = pat

with scope solely to the right of the as-pattern. Alternately, it might be compared to an equality constraint (x ~ pat).

Trac metadata
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Version 6.11
Type FeatureRequest
TypeOfFailure OtherFailure
Priority normal
Resolution Unresolved
Component Compiler (Parser)
Test case
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Reference: ghc/ghc#3545