I missed out on the discussion about multiple parameter type classes
last time round, so I'm pleased to have another chance to say my piece.
I added multiple parameter classes to Gofer at a time when there
was quite a lot of discussion on this list about such classes.
I'd been involved in
The main implementation problem is extending instance lookup to cover
multiple type constructors. The prototype Glasgow compiler was
designed to allow this, and I believe hbc also does this (as well as
Gofer, of course), so it's not a big issue!
No, hbc don't do this (yet). But the
