Alexey Rodriguez:
On Fri, Jul 4, 2008 at 5:03 AM, Manuel M T Chakravarty <[EMAIL PROTECTED]
> wrote:
The problem is that blah's type is ambiguous, as f does only occur
as an argument to the type family. If you'd define
class Blah f a where
blah :: a -> f -> T f f a
(and change the r
On Fri, Jul 4, 2008 at 5:03 AM, Manuel M T Chakravarty <[EMAIL PROTECTED]>
wrote:
> The problem is that blah's type is ambiguous, as f does only occur as an
> argument to the type family. If you'd define
>
> class Blah f a where
>blah :: a -> f -> T f f a
>
> (and change the rest of the prog
Alexey Rodriguez:
We are having trouble with the following program that uses type
families:
> class Blah f a where
> blah :: a -> T f f a
> class A f where
> type T f :: (* -> *) -> * -> *
the following function does not type:
> wrapper :: forall a f . Blah f a => a -> T f f a
> wrapper
On Thu, Jul 3, 2008 at 7:31 PM, Claus Reinke <[EMAIL PROTECTED]>
wrote:
> GHC gives the error:
>>
>> Couldn't match expected type `T f1 f1 a'
>> against inferred type `T f f a'
>> In the expression: blah x
>> In the definition of `wrapper': wrapper x = blah x
>>
>
> actually, GHC gi
GHC gives the error:
Couldn't match expected type `T f1 f1 a'
against inferred type `T f f a'
In the expression: blah x
In the definition of `wrapper': wrapper x = blah x
actually, GHC gives me "could not deduce Blah f a from Blah f1 a"
first. It seems that desugaring type fu
Hi guys,
We are having trouble with the following program that uses type families:
> class Blah f a where
> blah :: a -> T f f a
> class A f where
> type T f :: (* -> *) -> * -> *
the following function does not type:
> wrapper :: forall a f . Blah f a => a -> T f f a
> wrapper x = blah x
