c linked list

main.c

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

typedef struct _LinkedList {
    void *head;
    struct _LinkedList *tail;
} LinkedList;

LinkedList* list_tail(void) {
    return NULL;
}

LinkedList* list_cons(void *head, LinkedList *tail) {
    LinkedList* list = malloc(sizeof(LinkedList));
    list -> head = head;
    list -> tail = tail;
    return list;
}

void list_free(LinkedList *list) {
    if (list != NULL) {
        free(list -> head);
        list_free(list -> tail);
        free(list);
    }
}

int list_len(LinkedList *list) {
    if (list == NULL) {
        return 0;
    } else {
        return 1 + list_len(list -> tail);
    }
}

void* list_get(LinkedList *list, int i) {
    if (i == 0) {
        return list -> head;
    } else {
        return list_get(list -> tail, i - 1);
    }
}

void list_set(LinkedList *list, int i, void *x) {
    if (i == 0) {
        free(list -> head);
        list -> head = x;
    } else {
        list_set(list -> tail, i - 1, x);
    }
}

int* malloc_int(int x) {
    int *p = malloc(sizeof(int));
    *p = x;
    return p;
}

void list_int_print(LinkedList *list) {
    if (list == NULL) {
        printf("\n");
    } else {
        printf("%d, ", *(int*)(list -> head));
        list_int_print(list -> tail);
    }
}

int main(int argc, char *args[])
{
    LinkedList *list = list_cons(malloc_int(10), list_cons(malloc_int(5), list_cons(malloc_int(4), list_tail())));
    printf("len: %d\n", list_len(list));
    printf("list[2]: %d\n", *(int*)(list_get(list, 2)));
    list_int_print(list);
    list_set(list, 1, malloc_int(100));
    list_int_print(list);
    list_free(list);
    return 0;
}