[Haskell-cafe] Problem trying to get class Bounded to work

Bulat Ziganshin bulat.ziganshin at gmail.com
Tue May 23 02:20:22 EDT 2006

Hello Brian,

Tuesday, May 23, 2006, 4:05:45 AM, you wrote:

> Thanks for the solutions. The GHC scoped typed variables seem to be the best
> solution since they would seem to be the only way to implement something
> where the type only occurs in the result eg (if the actual fonts were to be
> added later):

>    createMonoMultiFont
>        :: forall i m . (MonadException m, Enum i, Bounded i)
>        => m (MonoMultiFont i)

malloc :: Storable a => IO (Ptr a)
malloc  = doMalloc undefined
    doMalloc       :: Storable b => b -> IO (Ptr b)
    doMalloc dummy  = mallocBytes (sizeOf dummy)

these tricks are better if you need to write code that will be
compiled not only by GHC. and i also hope that Haskell' will support
scoping of type variables over the function body

Best regards,
 Bulat                            mailto:Bulat.Ziganshin at gmail.com

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