my utils for string in ReasonML.

StringUtils.re

let split = (string) => {
  let rec toList = (l, i) => 
  switch (i) {
  | 0 => l
  | num => toList([string.[num - 1], ...l], num - 1)
  };
  toList([], string |> String.length)
};

let join = (charlist) => {
  let rec toString = (s, i) =>
  switch(i) {
  | 0 => s
  | num => toString((List.nth(charlist, i - 1) |> String.make(1)) ++ s, i - 1)
  };
  toString("", charlist |> List.length)
};