Help me I'm drowning in Functional

word_count.ml

module StringMap = Map.Make(String);;
let update_count key map = try StringMap.add key ((StringMap.find key map) + 1) map with | Not_found -> StringMap.add key 1 map;;
(* This is like List.fold_left but I can't seem to get the types to match up with
List.fold_left... *)
let rec accumulate map = function (* Same as match x with ... *)
	(* nothing to update, just return the map *)
	(* update count, then handle rest *)
	| [] -> map | h :: rest -> accumulate (update_count h map) rest;;

(* Booo *)
let count_words words = List.fold_left update_count StringMap.empty words
(* accumulate StringMap.empty words*);;

let counts = StringMap.bindings (count_words ["bark";"bark";"woof";"bark";"woof";"pant"]);;
List.iter ( fun ( x, y ) -> print_string x; print_string " "; print_int y; print_string "\n" ) counts;;