#ifndef EXPR_H
#define EXPR_H

#define MAX_SYMBOL_LEN 32U

#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

typedef struct {
	char buf[MAX_SYMBOL_LEN];
	size_t len;
} symbol_t;

typedef enum {
	ATOM_TYPE_EMPTY_LIST,
	ATOM_TYPE_INTEGER,
	ATOM_TYPE_SYMBOL,
} atom_type_t;

typedef struct {
	atom_type_t type;
	union {
		int64_t integer;
		symbol_t symbol;
	};
} atom_t;

struct expr;

typedef struct {
	struct expr *car, *cdr;
} pair_t;

typedef struct expr {
	bool is_atom;
	union {
		atom_t atom;
		pair_t pair;
	};
} expr_t;

#endif