Re: [Haskell-cafe] nice simple problem for someone struggling....

[Miguel Mitrofanov]

module Main where

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!
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