On Mon, Jul 24, 2017 at 4:55 AM, Panicz Maciej Godek <xxxxxx@gmail.com> wrote:

(is _ < x < y) is allowed, but it is bad programming style: within the scope of this expression,
(< x y) already has a definite value which doesn't have to be evaluated every time the function
is called.

It doesn't have a definite value if x and/or y are mutable variables or non-pure expressions; in such case (< x y) has to be evaluated every time.

That's why srfi-26 has cut and cute.