]> I have an error I don't quite understand. Can someone give me a clue? I get an error in the following code: module StringSet = Set.Make(String);; let main() = let allFields = Fileutils.fold_file_lines (fun l m -> StringSet.add l m) StringSet.empty Sys.argv[1] in print_endline("All fields --"); StringSet.iter print_endline allFields; print_endline("/All fields --"); ;; It fails to compile on the due to the the following error (where 18/30-31 is the m in ``(fun l m -> StringSet.add l m)'' File "spreadsheetPivot.ml", line 18, characters 30-31: This expression has type 'a -> 'b but is here used with type StringSet.t = Set.Make(String).t The documentation for fold_file_lines looks like this: ``val fold_file_lines : (string -> 'a -> 'a) -> 'a -> string -> 'a'' and I know ``StringSet.add "hello" StringSet.empty'' works. fold_file_lines is defined as let fold_file_lines f init_value fn = operate_on_file (fold_lines f init_value) fn ;; where operate_on_file is let operate_on_file f fn = let ch = open_in fn in try let rv = f ch in close_in ch; rv with x -> close_in ch; raise x ;; and fold_lines is let rec fold_lines f init_value ch = let line,eof = try (input_line ch), false with End_of_file -> "", true in if eof then init_value else fold_lines f (f line init_value) ch ;; -- Dustin Sallings ------------------- 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