... I spent 10 years programming in prolog before I tried haskell. Most of my problems with haskell are because it has a rather opaque performance model (e.g. when should you use tail recursion, and when should you not). But I happily acknowledge that my experience is probably atypical. ;-)
Hmmmm.... After 10 years you should have under your skin the feeling when you would like to use backtracking, and when the "forward", recursive loop in Prolog, don't you? Well, it requires just a little twist to acquire a similar feeling with Haskell: when should one loop using tail recursion, and when it is preferable to act incrementally, deferring the construction of a data piece until its consumption. Prolog was one of the first languages I learnt (centuries ago, when it used the Marseille syntax...), and I must say that it *helped* me with Haskell. But anyway, programming languages require first a good deal of positive thought. The discussion on the relative merits of X or Y is OK, but when I read that someone hates Perl, and somebody else hates Matlab, I am a bit sick. Hatred never produced anything. Jerzy Karczmarczuk