#include <stdio.h>
#include "intlist.h"

int member(intlist_t l, int val)
{
  return isempty(l) ? 0 : val == head(l) || member(tail(l), val);
}

int member_it(intlist_t l, int val)
{
  while (!isempty(l))
    if (val == head(l)) return 1;
    else l = tail(l);
}

int sum_it(intlist_t l)
{
  int sum = 0;
  while (!isempty(l)) {
    sum = sum + head(l);
    l = tail(l);
  }
}

int sum(intlist_t l)
{
  return isempty(l) ? 0 : head(l) + sum(tail(l));
}

int sum2(intlist_t l, int part)
{
  return isempty(l) ? part : sum2(tail(l), part + head(l));
}

intlist_t rev2(intlist_t l, intlist_t done)
{
  if (isempty(l)) return done;
  int hd;
  intlist_t tl;
  split(l, &hd, &tl);
  return rev2(tl, cons(hd, done));
}

intlist_t rev(intlist_t l)
{
  return rev2(l, emptylist());
}

void printlist(intlist_t l)
{
  if (isempty(l)) printf(".\n");
  else {
    printf("%d->", head(l));
    printlist(tail(l));
  }
}

void delete(intlist_t l)
{
  if (!isempty(l)) {
    int hd;
    intlist_t tl;
    split(l, &hd, &tl);
    delete(tl);
  }
}

void iter(intlist_t l, void (*f)(int))
{
  if (!isempty(l)) {
    f(head(l));
    iter(tail(l), f);
  }
}

void printel(int n) { printf("%d->", n); }
 
void printlist2(intlist_t l)
{
  iter(l, printel); 
}

void printlist1(intlist_t l)
{
  printlist2(l);
  printf(".\n");
}

int main(void)
{
  intlist_t l = cons(1, cons(2, cons(3, cons(4, emptylist()))));
  printlist1(l);
  printf("%d\n", sum(l));
  intlist_t lr = rev(l);
  printlist1(lr);
  delete(lr);
  return 0;
}