ocaml prologue for HackerRank (reading ints, |>, etc)

gistfile1.ml

let (|>) v f = f v;;

let string_of_char_list (ls : char list) : string =
  let s = String.make (List.length ls) '0' in
    List.fold_left (fun i c -> s.[i] <- c; i+1) 0 ls;
    s;;

let append_string (xs : string list) (ls : char list) : string list =
  let s = string_of_char_list ls in
    if String.length s = 0 then xs else (xs @ [s]);;

let read_words_on_line (sep:char -> bool) (s:string) : string list =
  let len = String.length s in
  let rec aux i cs acc =
    if i = len then
      append_string acc cs
    else
      let c = s.[i] in
      let cs, acc =
        if sep c then
          [], append_string acc cs
        else
          (cs @ [c]), acc in
      aux (i+1) cs acc in
  aux 0 [] [];;

let is_space = String.contains " \n\r";; (* apparently they use \r too *)

let read_ints () = read_line () |> read_words_on_line is_space |> List.map int_of_string;;