|
|
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:jules@xxxxxxxxxxxxxxx]
Sent: 21 December 2007 15:33
To: Nicholls, Mark
Cc: haskell-cafe@xxxxxxxxxxx
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@xxxxxxxxxxx
http://www.haskell.org/mailman/listinfo/haskell-cafe
|
|