Yes sorry….but this still fails with….

“`numberType1' is a rigid type variable bound by”

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From: Brent Yorgey [mailto:byorgey@gmail.com]
Sent: 21 December 2007 17:29
To: Nicholls, Mark
Cc: Jules Bean; haskell-cafe@haskell.org
Subject: Re: [Haskell-cafe] nice simple problem for someone struggling....

"class ShapeInterface shape where
       area :: shape->Int"

now looks dubious....I want it to be something like

"class ShapeInterface shape where
       area :: Num numberType => shape->Int" ?

Rather, I think you probably want

class ShapeInterface shape where
    area :: Num numberType => shape -> numberType

-Brent