[Haskell-beginners] How to link two Types

[David McBride]

It is hard to tell from your code what you intend, but it works
however you want it to, so long as it type checks.

class Frame a where
  type Whatever a
  len :: Whatever a -> IO (Maybe Int)
  row :: Whatever a -> MaybeT IO (DifTomoFrame a DIM1)

instance Frame DataFrameH5Path  where
  type Whatever DataFrameH5Path = DataFrameH5
  len = undefined -- :: DataFrameH5 -> IO (Maybe Int)
  row = undefined -- :: DataFrameH5 -> Int -> MaybeT (DifTomoFrame
DataFrameH5Path DIM1)



On Wed, Feb 22, 2017 at 11:19 AM, PICCA Frederic-Emmanuel
<frederic-emmanuel.picca at synchrotron-soleil.fr> wrote:
> Hello thanks, I will investigate, but I like this solution.
> I can ad more type to a type family right ?
>
>
> Is it possible with this type family to be able to link in the other way ?
>
> a -> t
>
> Cheers
>
> Fred
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners