open Core.Std

type primitive = Add | Sub | Mul | Div | Int of int

let re_int = Str.regexp "^[-]?[0-9]+$"

let primitive_of_string s =
  if (Str.string_match re_int s) 0 then Int (int_of_string s)
  else if s = "+" then Add
  else if s = "-" then Sub
  else if s = "*" then Mul
  else if s = "/" then Div