Hello Simeon, Monday, March 31, 2008, 12:45:54 AM, you wrote:
The latter specifies a lexicographic order: Constructors are ordered by the order of their appearance the data declaration, and the arguments of a constructor are compared from left to right.
Although I have tried to make sense what lexicographic order means I haven't figured out. Maybe an example with a simple application of this would be helpful. To be honest I can't understand what the symbol <= really means.
i'm not sire that i understood your question (are you really never seen less-or-equal comparison? :), but i can say about lex. order: if you can compare chars and 'a' < 'b', then *lists* of chars compared in lexicographic order will be "aaa" < "aab" "aab" < "aba" "baa" < "abb" and so on - i.e. it finds *left-most* pair of non-equal chars and returns result based on it comparison the same principle used for comparison of these trees - any Leaf smaller than any Branch, if the same constructors are used then their parameters are compared, from left to right 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' ? -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com