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

struct closure {
  void (* call)(struct closure *);

  int x;
};

void block(struct closure * env) {
  env->x += 1;
  printf ("block: x is %d\n", env->x);
}

struct closure * foo(int x)
{
  struct closure * closure = (struct closure *)malloc(sizeof(struct closure *));
  closure->x = x;

  printf ("x is %d\n",closure->x);

  closure->call = &block;

  return closure;
}

int main() {
  struct closure * c = foo(5);

  c->call(c);
  c->call(c);
}