[Haskell-cafe] Re: Type family problem

Gleb Alexeyev gleb.alexeev at gmail.com
Wed Jan 21 06:51:44 EST 2009


Sjoerd Visscher wrote:
> When I try this bit of code:
> 
>  > class C1 a where
>  >   type F a :: *
>  >   x :: F a
>  >   y :: F a
>  >   x = y
> 
> I get this error:
> 
>     Couldn't match expected type `F a1' against inferred type `F a'
>     In the expression: y
>     In the definition of `x': x = y
> 
> I can't figure out what is going on or how I should fix this.
> 

The discussion [1] seems to be related.

[1] http://hackage.haskell.org/trac/ghc-test/ticket/2855



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