I'd rather not do that, but even if I did, the type-variable action would not be reachable in the terminal function. I could specify a functional dependency st -> action (though I've never used it, it would be a fun to learn). I'm curious as to why my class declaration compiles in GHC, as there doesn't seem to be any way to use it. -Arjun On Aug 7, 2004, at 01:06, camarao@dcc.ufmg.br wrote:
Hi Arjun.
How about inserting one more parameter, "action", in your class definition:
class (Ord st) => MinimaxState st action where successors:: st -> [(action,st)] terminal:: st -> Bool
instance MinimaxState Int Int where terminal i = i == 0 successors i = [(1,i+1), (-1,i-1)]
Then don't forget to start the compiler/interpreter with -fglasgow-exts.
Hope this helps.
Regards,
Carlos