[Haskell-cafe] RealFloat constraint on Complex type

[Richard A. O'Keefe]

On 21 May 2008, at 9:25 am, Conal Elliott wrote:
> I think the practice of constraint in type definitions is generally  
> discouraged,

Is this true?  If so, why?
If I have a data type that simply doesn't make sense unless some of the
type variables belong to certain classes, _shouldn't_ that be stated
clearly in the declaration rather than hidden elsewhere?

--
"I don't want to discuss evidence." -- Richard Dawkins, in an
interview with Rupert Sheldrake.  (Fortean times 232, p55.)