Closure in C

closure.c

#include <stdio.h>

typedef struct TClosure {
    int (*code)(struct TClosure *env, int);
    int state;
} Closure;


int call(Closure *c, int x) {
    return c->code(c, x);
}


int adder_code(Closure *env, int x) {
    return env->state + x;
}


int multiplier_code(Closure *env, int x) {
    return env->state * x;
}


Closure make_closure(int op, int k) {
    Closure c;
    c.state = k;
    c.code = (op == '+' ? adder_code : multiplier_code);
    return c;
}


int main(int argc, const char *argv[]) {
    Closure c1 = make_closure('+', 10);
    Closure c2 = make_closure('*', 3);
    printf("c1(3) = %i, c2(3) = %i\n",
           call(&c1, 3), call(&c2, 3));
    return 0;
}