#3545: As-patterns for type signatures
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Reporter: LouisWasserman | Owner:
Type: feature request | Status: new
Priority: normal | Component: Compiler (Parser)
Version: 6.11 | Severity: normal
Keywords: | Testcase:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
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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).
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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3545>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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