headers
Miguel Mitrofanov | 21 Dec 19:11
Picon
Favicon

Re: nice simple problem for someone struggling....

module Mainwhere

 

data SquareType numberType = Num numberType => SquareConstructor numberType

 

class ShapeInterface shape where

      area :: Num numberType => shape->numberType

 

data ShapeType = forall a. ShapeInterface a => ShapeType a

 

instance (Num a) => ShapeInterface (SquareType a) where

    area (SquareConstructor side) = side * side

Awesome! That's the first e-mail I see that looks good in HTML!
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe <at> haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
Permalink | Reply |

Gmane