Project Euler #22

#load "str.cma";;

let char_value c = (int_of_char c) - (int_of_char 'A') + 1;;

let word_value s =
  let word_length = String.length s in
  let rec sum_letters s n =
    if n == 0 then
      char_value s.[0]
    else
      (char_value s.[n]) + (sum_letters s (n-1))
  in
  sum_letters s (word_length - 1);;

let line_stream_of_channel channel =
  Stream.from
    (fun _ -> 
      try Some (input_line channel) 
      with End_of_file -> None);;

let lines datafile =
  let xs = ref [] in
  Stream.iter
    (fun x -> xs := x :: !xs)
    (line_stream_of_channel (open_in datafile));
  List.rev !xs;;

let content = List.sort (String.compare)
    (List.map 
       (fun x -> 
     let l = String.length x 
     in 
     String.sub x 1 (l - 2)) 
       (List.concat 
      (List.map
         (Str.split 
        (Str.regexp_string ","))
             (lines (Sys.argv.(1))))));;

let rec sum l n = match l with
  h :: t -> ((word_value h) * n) + (sum t (n+1))
| [] -> 0;;
       
Printf.printf "%d\n" (sum content 1)