Alastair Reid
Anyway, isn't there some kind of collection class that FM can be made a member of?
Curiously, it seems classes aren't used much in the libraries. I.e. I wanted my data structure to be used more or less like an array (it was basically an array with some extras), but I couldn't just instance Indexed Foo where a ! i = ... bounds a = ... I can of course always define operations using different names, but IMHO reusing common ones, like (!) makes the code much more readable. Similar for Sets, lists, and FMs, I'd expect something like instance Collection a where empty = ... (!!) cardinality -- or whatever and so on. It is quite possible that there are technical difficulties defining good, generic classes like this, and that I haven't looked deeply enough into the matter -- I vaguely remember a posting from Chris Okasaki about classes in the Edison library regarding this. OTOH, I find I define classes very sparingly in my own programming. Comong from an OO world I started out with a desire to create classes for just about anything, but in practice, it rarely seems necessary. So while it still can be useful or desirable, it just doesn't get done. -kzm -- If I haven't seen further, it is by standing in the footprints of giants