Manuel M T Chakravarty writes:
Another thing, here's an excerpt of the current summary of the MPTC dilemma from http://haskell.galois.com/cgi-bin/haskell-prime/trac.cgi/wiki
Multi Parameter Type Classes Dilemma ¦
Options for solving the dilemma ¦ 2. Put AssociatedTypes on the fast-track for sainthood
Associated Types ¦
Cons ¦ * Only a prototype implementation so far
This is a *inaccurate* and highly *misleading* summary.
I didn't write that wiki page plus you are citing individual sentences out of a larger text.
This wasn't meant as a "personal attack". If you (or whoever wrote) feel offended, I'm sorry. Fact is: (risking that I repeat myself here) - When it comes to typing, FDs strictly subsume ATs. (FDs = as defined in the FD-CHR paper) FYI, the next Chameleon release will supports FDs and ATs, ATs are internally represented via FD-CHRs. - All the challenging inference problems encountered for FDs also apply to ATs (see my previous emails) - FD-CHRs describe improvement *and* instance, superclass rules. It's really the subtle interaction between improvement and instances that causes the problem. I also would like to point that none of the FD-CHR results are "recent". The FD-CHR paper was published in ESOP'04, that was two years ago. Since April 2004, there's an extended version available as a TR. Correct, a revised version will somewhen soon appear as a JFP paper. Martin