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


struct env {
  int x;
};

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

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

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

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

  struct closure closure;
  closure.env = env;
  closure.call = block;

  return closure;
}

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

  c.call(c.env);
  c.call(c.env);
}