struct Foo(x:Int, y:Int)
	func len(f:Foo->Num)
		return Num.sqrt(Num(f.x*f.x + f.y*f.y))!

func main()
	assert (3 _min_ 5) == 3
	assert (5 _min_ 3) == 3

	assert (Foo(5, 1) _min_ Foo(5, 999)) == Foo(x=5, y=1)

	assert (Foo(5, 999) _min_.x Foo(5, 1)) == Foo(x=5, y=999)

	assert (Foo(999, 1) _min_.y Foo(1, 10)) == Foo(x=999, y=1)

	assert (Foo(-999, -999) _max_.len() Foo(10, 10)) == Foo(x=-999, y=-999)

	>> foos := [Foo(5, 1), Foo(5, 99), Foo(-999, -999)]
	assert (_max_: foos)! == Foo(x=5, y=99)