2008/3/30, Bulat Ziganshin <[EMAIL PROTECTED]>: > although the last alternative, > (Branch l r) <= (Branch l' r') = l == l' && r <= r' || l <= l' > seems suspicious to me. isn't it the same as > (Branch l r) <= (Branch l' r') = l <= l'
Yes, it should be : (Branch l r) <= (Branch l' r') = l < l' || l == l' && r <= r' Lexical order for a tuple (a,b) is : (a,b) <= (a',b') iff (a < a' or (a == a' and b <= b')) The same idea can be applied to list (where Nil is strictly less than anything else) or other datatypes. -- Jedaï _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
