Really....I'm sure I tried that...(as it seemed obvious) ... and it failed....but I'll have another go....
-----Original Message----- From: Jules Bean [mailto:[EMAIL PROTECTED] Sent: 21 December 2007 15:33 To: Nicholls, Mark Cc: haskell-cafe@haskell.org Subject: Re: [Haskell-cafe] nice simple problem for someone struggling.... Nicholls, Mark wrote: > *instance* ShapeInterface SquareType *where* > > area (SquareConstructor sideLength) = sideLength * sideLength > *data* SquareType a = Num a => SquareConstructor a Now you have changed your type from SquareType to SquareType a, you need to change the instance to: instance ShapeInterface (SquareType a) where... Jules _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
