#2187: Top-level bindings are broken for polymorphic values
------------------------+---------------------------------------------------
Reporter: yallop | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.8.2 | Severity: major
Keywords: | Testcase:
Architecture: Unknown | Os: Unknown
------------------------+---------------------------------------------------
Top-level pattern bindings don't work for polymorphic values. Here's an
example program:
{{{
[x] = [id]
}}}
ghci gives this the type
{{{
*Main> :t x
x :: GHC.Prim.Any -> GHC.Prim.Any
}}}
which can't be used
{{{
*Main> x ()
<interactive>:1:2:
Couldn't match expected type `GHC.Prim.Any'
against inferred type `()'
In the first argument of `x', namely `()'
In the expression: x ()
In the definition of `it': it = x ()
}}}
Adding a type signature doesn't help:
{{{
x :: a -> a
[x] = [id]
Couldn't match expected type `forall a. a -> a'
against inferred type `a -> a'
Probable cause: `id' is applied to too few arguments
In the expression: id
In the expression: [id]
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2187>
GHC <http://www.haskell.org/ghc/>
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