Phil Wadler writes:
The GRASP team at Glasgow is putting the finishing touches on a paper
that formally describes type classes as implemented in Haskell, which
you may find helpful. We will post a pointer to this paper when it's
done. I hope Mark Jones and Martin Odersky will also post pointers to
their recent work in this area.
Kung Chen, Paul Hudak, and I have looked into the problem of extending
Haskell's type system such that container type classes become
possible. Examples of such classes are "Sequence" (with instance types
List and Array, for instance), or "Monad". Last year, there was some
discussion on this mailing list as to whether this requires
second-order unification. Well, fortunately it doesn't. The results
are found in the paper "Parametric Type Classes". It can be picked up
by anonymous ftp from
nebula.cs.yale.edu directory: pub/haskell/papers
-- Martin
