repl.c

#include <stdio.h>
#include <stdlib.h>
#include <mpc.h>

#include <readline/readline.h>
#include <readline/history.h>

int main (int argc, char** argv) {
  mpc_parser_t* Number   = mpc_new("number");
  mpc_parser_t* Operator = mpc_new("operator");
  mpc_parser_t* Expr     = mpc_new("expr");
  mpc_parser_t* Lispy    = mpc_new("lispy");

  mpca_lang(MPCA_LANG_DEFAULT, "                 \
number  : /-?[0-9]*\\.?[0-9]+/ ;                 \
operator: '+' | '-' | '*' | '/';                 \
expr    : <number> | '(' <operator> <expr>+ ')' ;\
lispy   : /^/ <operator> <expr>+ /$/;            \
", Number, Operator, Expr, Lispy);

  puts ("Maybe a Lisp 0.1.0");
  puts ("ctrl+c to exit\n");

  while (1) {
    char* input = readline("honk> ");
    add_history(input);

    mpc_result_t r;
    if (mpc_parse("<stdin>", input, Lispy, &r)) {
      mpc_ast_print(r.output);
      mpc_ast_delete(r.output);
    } else {
      mpc_err_print(r.error);
      mpc_err_delete(r.error);
    }
    free(input);
  }
  mpc_cleanup(4, Number, Operator, Expr, Lispy);
  return 0;
};