Error: Invalid Conversion `bool' to `list_node*'

main.cpp:83: error: invalid conversion from `bool' to `list_node*'
main.cpp:83: error: initializing argument 1 of `void write_list(list_node*)'

I can't seem to fix this error

Code:

     // equal
     cout << "Enter two lists for equal: ";
     p = read_list();
     q = read_list();
     write_list( equal(p, q) );

Code:

bool equal(list p, list q)
   {
   if (is_null(p) && is_null(q)) return true;
   if (is_null(p) || is_null(q)) return false;
   if (atom(car(p)) != atom(car(q))) return false;
   if (atom(car(p)))
   return eq(car(p), car(q)) && equal(cdr(p), cdr(q));
   return (equal(car(p), car(q)) && equal(cdr(p), cdr(q)));
   }

Code:

write_list( equal(p, q) );

write_list() probably expects a 'list_node*', and you're passing it a bool (since that's what equal returns).