#include <stdio.h>
#include <stdlib.h>
typedef struct list_ {
int x;
struct closure_int_int_list_ *tail;
} *list;
typedef struct closure_int_int_list_ {
list (*call)(int, int);
int x1;
int x2;
} *closure_int_int_list;
closure_int_int_list newclosure(list call(int, int), int x1, int x2)
{
closure_int_int_list c;
c = (closure_int_int_list)malloc(sizeof(*c));
c->call = call;
c->x1 = x1;
c->x2 = x2;
return c;
}
list newlist(int x, closure_int_int_list tail)
{
list xs = (list)malloc(sizeof(struct list_));
xs->x = x;
xs->tail = tail;
return xs;
}
list listtail(list xs)
{
if (xs->tail == NULL) return NULL;
return xs->tail->call(xs->tail->x1, xs->tail->x2);
}
void deletelist(list xs)
{
free(xs->tail);
free(xs);
}
int *takelist(int num, list xs)
{
int *array;
int i;
list p;
array = (int *)malloc(sizeof(int) * num);
p = xs;
for (i = 0; i < num; ++i) {
array[i] = p->x;
p = listtail(p);
}
return array;
}
list fibnext(int a, int b)
{
return newlist(b, newclosure(fibnext, b, a + b));
}
void printarray(int *xs, int size)
{
int i;
for (i = 0; i < size; ++i) {
printf("%d ", xs[i]);
}
}
int main(int argc, char const* argv[])
{
list xs;
int *array;
xs = newlist(1, newclosure(fibnext, 1, 1));
array = takelist(10, xs);
printarray(array, 10);
free(array);
deletelist(xs);
return 0;
}
result:
1 1 2 3 5 8 13 21 34 55
