foldl_sum.c

gistfile1.c

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

typedef struct _list {
    int d;
    struct _list *next;
} list;
typedef int(*func)(list*, int);

list* new_list() {
    list *nl = (list*)malloc(sizeof(list));
    nl->d = -1;
    nl->next = NULL;
    return nl;
}

list* push(list* l, int i) {
    list *nl = new_list();
    nl->d = i;
    nl->next = l;
    return nl;
}

int f(list *i, int acc) {
    return acc + i->d;
}
int foldl(func fun, int acc, list *l) {
    return l->d == -1? acc: foldl(fun, fun(l, acc), l->next);
}
int main(int argc, char *argv[]) {
    list *l = push(push(push(push(new_list(), 1), 2), 3), 4);
    printf("%d\n", foldl(f, 0, l));
    return 0;
}