object.c

/*
 * Lists
 */
struct cons {
  ref_t car, cdr;
};

ref_t make_cons(ref_t car, ref_t cdr) {
  struct cons *ptr = safe_malloc(sizeof(struct cons));
  ptr->car = car, ptr->cdr = cdr;
  return ((ref_t) ptr) | LIST_MASK;
}

ref_t car(ref_t obj) {
  assert(islist(obj));
  return ((struct cons *) (obj ^ LIST_MASK))->car;
}

ref_t cdr(ref_t obj) {
  assert(islist(obj));
  return ((struct cons *) (obj ^ LIST_MASK))->cdr;
}

print.c

static void printlist(ref_t obj) {
  ref_t thecar = car(obj);
  ref_t thecdr = cdr(obj);
  print(thecar);
  if (isnil(thecdr))
    ;
  else if (islist(thecdr)) {
    putchar(' ');
    printlist(thecdr);
  } else {
    printf(" . ");
    print(thecdr);
  }
}

void print(ref_t obj) {
  if (isnil(obj))
    printf("nil");
  else if (istrue(obj))
    printf("true");
  else if (isfixnum(obj))
    printf("%i", fixnum_to_int(obj));
  else if (islist(obj)) {
    putchar('(');
    printlist(obj);
    putchar(')');
  }
  else
    printf("0x%x", obj);
}

void println(ref_t obj) {
  print(obj);
  puts("");
}