Right-associative parital application

partial_right.js

// Some assertion functions we can play with
function assert(condition, message) {
  if(!condition) {
    throw new Error(message);
  }
}
 
function assert_equal(obj1, obj2) {
  assert(obj1 === obj2, 'Expected '+obj1+' to equal '+obj2+'.');
}

/***************************************************************************
 * Implement right-associateive partial application:                       *
 **************************************************************************/

function partial_right(fn) {
	// fill in here
}

function complex(a,b,c,d) { return (a+b+c)/d; }

var complexWith2   = partial_right(complex, 2);
// complexWith2(1,2,3) === complex(1,2,3,2);

var complexWith4_2 = partial_right(complex, 4,2);
// complexWith4_2(1,2) === complex(1,2,4,2);

assert_equal(typeof complexWith2, 'function');
assert_equal(complexWith2(1,2,3), 3);
assert_equal(complexWith2(33,34,33), 50);
assert_equal(complexWith2(4,4,4), 6);

assert_equal(typeof complexWith4_2, 'function');
assert_equal(complexWith2(4,4), 6);
assert_equal(complexWith2(12, 16), 16);
assert_equal(complexWith2(7, 7), 8);