mpc_parser_t* Integer  = mpc_new("integer");
        mpc_parser_t* Double   = mpc_new("double");
        mpc_parser_t* Symbol   = mpc_new("symbol");
        mpc_parser_t* Sexpr    = mpc_new("sexpr");
        mpc_parser_t* Expr     = mpc_new("expr");
        mpc_parser_t* Lispy    = mpc_new("lispy");

  const char *grammar = 
    "                                                                                         \n\
      double   : /-?[0-9]+.[0-9]+/ | ;                                                        \n\
      integer  : /-?[0-9]+/ | ;                                                               \n\
      symbol   : '+' | '-' | '*' | '/' | '%' | '^' | \"min\" | \"max\" | \"inc\" | \"dec\" ;  \n\
      sexpr    : '(' <expr>* ')' ;                                                            \n\
      expr     : <double> | <integer> | <symbol> | <sexpr> ;                                  \n\
      lispy    : /^/ <expr>* /$/ ;                                                            \n\
    \n";

  printf("Grammar: %s\n", grammar);

  mpca_lang(MPC_LANG_DEFAULT, grammar,
      Double, Integer, Symbol, Sexpr, Expr, Lispy);