lexer.mll

(* lowercase definition *)
let lowercase = ['a'-'z' '_']

(* identchar definition *)
let identchar = ['A'-'Z' 'a'-'z' '_' '\'' '0'-'9']

(* Some stuff before *)
| lowercase identchar * as name
      { try Hashtbl.find keyword_table name
        with Not_found -> LIDENT name }
| lowercase_latin1 identchar_latin1 * as name
      { warn_latin1 lexbuf; LIDENT name }
(* Some stuff after *)