#4356: type instance doesn't work when the type is (->)
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Reporter: sjoerd_visscher | Owner: simonpj
Type: bug | Status: new
Priority: high | Milestone: 7.0.1
Component: Compiler (Type checker) | Version: 7.1
Keywords: | Testcase:
Blockedby: | Difficulty:
Os: MacOS X | Blocking:
Architecture: x86_64 (amd64) | Failure: GHC rejects valid
program
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Changes (by igloo):
* owner: => simonpj
* priority: normal => high
* milestone: => 7.0.1
Old description:
> This doesn't work in 7.0.0.20100924.
> It works fine in 6.12.3.
>
> {-# LANGUAGE TypeFamilies #-}
> type family T t :: * -> * -> *
> type instance T Bool = (->)
> f :: T Bool Bool Bool
> f = not
>
> This is the error:
>
> Couldn't match type `T Bool' with `(->)'
> Expected type: T Bool Bool Bool
> Actual type: Bool -> Bool
> In the expression: not
> In an equation for `f': f = not
New description:
This doesn't work in 7.0.0.20100924.
It works fine in 6.12.3.
{{{
{-# LANGUAGE TypeFamilies #-}
type family T t :: * -> * -> *
type instance T Bool = (->)
f :: T Bool Bool Bool
f = not
}}}
This is the error:
{{{
Couldn't match type `T Bool' with `(->)'
Expected type: T Bool Bool Bool
Actual type: Bool -> Bool
In the expression: not
In an equation for `f': f = not
}}}
--
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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4356#comment:2>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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