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%{
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "lisp_api.h"
#include "lisp.h"
int yylex(void);
int yyerror(const char *s);
void eval_and_print_REPL(value *v) {
if(!v) { return; }
if (v->type == VT_PAIR && car(v)->type == VT_SYMBOL && !strcmp(car(v)->as.sym, "define")) {
eval(global_env, v);
printf(";> defined ");
println_value(car(cdr(v)));
return; // Skip printing for define so infinite lists do not eval
}
printf(";> ");
println_value(eval(global_env, v));
}
%}
%union {
double dval;
const char *strval;
value *val;
}
%token <dval> NUMBER
%token <strval> STRING SYMBOL
%token LPAREN RPAREN DOT QUOTE
%type <val> expr atom list list_items
%start exprs
%%
exprs: /* nothing */
| expr { eval_and_print_REPL($1); }
| exprs expr { eval_and_print_REPL($2); }
expr: atom
| list
| LPAREN expr DOT expr RPAREN { $$ = cons($2, $4); }
| QUOTE expr { $$ = cons(make_symbol("quote"), cons($2, make_nil())); }
list: LPAREN list_items RPAREN { $$ = $2; };
list_items: /* empty list */ { $$ = make_nil(); }
| expr list_items { $$ = cons($1, $2); }
| expr DOT expr { $$ = cons($1, $3); };
atom: NUMBER
{
if(is_integer($1)) {
$$ = make_int($1);
} else {
$$ = make_double($1);
}
}
| STRING { $$ = make_string($1); };
| SYMBOL { $$ = make_symbol($1); };
%%
int yyerror(const char *s) {
printf("%s\n",s);
}
|
