1. цепочка вызовов
	pow(2,3) = 2 .pow 3 = (2,3) .pow;


																2. развертывание присваиваний
	ArraySet a = {1, 2, 3};
	BitSet a = {1, 2, 3};
	HashSet a = {1, 2, 3};
	
function lift: SET -> ArraySet{
	src -> foldl (src, include, ArraySet::EMPTY)
}

operator '=' = lift;

																3. вид функции:


square:   (Number, Number) -> Integer {
	(15, y) -> let{x = 1, y = 1, z=3}  x+ y+ z
}


{
	(15, y) : let{
			x = 1, y = 2, z=3
		} x*y*z,

	(x, 15) : x*y*z where {
			x = 1, y = 2, z=3
		}
}
	case  : let a = 16, 
		      b= 8, 
		  in 	a+b

switch (XXXX)
	case (_, 18) :