Ashley Yakeley <[EMAIL PROTECTED]> wrote
> OK, I understand it a bit better now. This code does not compile:
> --
> class X a
> instance X Bool
> instance (Num a) => X a
> --
> Can someone explain why the two instances overlap, given that Bool is not
> an instance of Num?
>
> Would it be possible for Haskell to figure out this sort of thing and not
> complain about it, or would that lead to nasty problems?
Think what would happen if someone had a module that did define
Bool as an instance of Num and imported the class X.
--
J�n Fairbairn [EMAIL PROTECTED]
31 Chalmers Road [EMAIL PROTECTED]
Cambridge CB1 3SZ +44 1223 570179 (after 14:00 only, please!)
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