part of migration to gc

byterun/include/builtin.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <stdio.h>
+
+#include "operations.h"
+
+inline void f_read(struct State *s) {
+  int x = 0;
+  printf("> "); // TODO: ??
+  scanf("%i", &x);
+  s_put_i(s, x);
+}
+
+inline void f_write(struct State *s) {
+  int x = s_take_i(s);
+  printf("%i", x);
+  // put 0 ??
+}
+
+inline void f_length(struct State *s) {
+  // TODO
+}
+
+inline void f_string(struct State *s) {
+  // TODO
+}
+
+inline void f_array(struct State *s, int sz) {
+  // TODO
+}
+
+inline void f_cons(struct State *s) {
+
+  // TODO
+}