On Tue, Jul 15, 2003 at 01:07:12AM -0700, Ashley Yakeley wrote: > In article <[EMAIL PROTECTED]>, > Marcin 'Qrczak' Kowalczyk <[EMAIL PROTECTED]> wrote: > > > It doesn't provide instances of Num for anything which is already an instance > > of the other classes. And in Haskell 98 they must be defined separately for > > each type, instance (...) => Num a doesn't work. > > It works in extended Haskell however, so I suspect it lays to rest the > question of needing some other language extension.
I disagree! This method (putting each function in its own class) does
not address two related points:
a) Being able to declare default values for a method declared in a
superclass;
b) Being able to refine a type heirarchy without the users noticing
(and without explosion of the number of instance declarations
required).
Peace,
Dylan
pgp00000.pgp
Description: PGP signature
