]> Can anyone explain to me why the following doesn't compile: ---------- type thing = Int of int | String of string ;; let int_of_thing t = match t with Int i -> i | String s -> int_of_string s ;; let string_of_thing t = match t with Int i -> string_of_int i | String s -> s ;; let compare_things t1 t2 comparison_fun = match (t1, t2) with (Int i, _) -> comparison_fun i (int_of_thing t2) | (String s, _) -> comparison_fun s (string_of_thing t2) ;; let is_less_than t1 t2 = compare_things t1 t2 (<) ;; let is_greater_than t1 t2 = compare_things t1 t2 (>) ;; ---------- The compiler says: File "test.ml", line 16, characters 38-39: This expression has type string but is here used with type int It seems to have decided that in the function compare_things, comparison_fun is int -> int -> 'a because that's how it's used in the first pattern, not realising that I mean to pass a polymorphic function, 'a -> 'a -> bool. Is there a way to make this work? (Specifying the type of comparison_fun as 'a -> 'a -> bool makes no difference.) Ben ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners