/********************
 * Expected output:
1
2
55
********************/
var tru = function(x,y) { x; };
var fls = function(x,y) { y; };

// Functions for pairs
var pair = function(x,y) {
  function(f) { f(x,y); };
};

var fst = function(p) { p(tru); };
var snd = function(p) { p(fls); };

var p = pair(1,2);
print(fst(p));
print(snd(p));

// Functions for lists
var cons = pair;
var head = fst;
var tail = snd;

var isEmpty = function(lst) {
  lst == null;
};

var nums = cons(1, cons(2, cons(3, cons(4, cons(5,
    cons(6, cons(7, cons(8, cons(9, cons(10, null))))))))));


var sumList = function(lst) {
  if (isEmpty(lst)) 0;
  else head(lst) + sumList(tail(lst));
};

print(sumList(nums));