cljs range fn does odd things with nil, is this a bug?

Question

In Clojure, passing a nil as the first arg to range throws NPE, but in ClojureScript it doesn't and odd things can happen:

(range nil 0)
=> ()
(range nil 1)
=> (nil)
(range nil 2)
=> (nil 1)

What's worse is if you have the start and the step both being nil:

(range 0 0 0)
=> ()
(range nil 0 nil)
INTERNAL REPL ERROR: Got an unexpected reply from relay, check Inspect
Timeout while waiting for result.

This actually evaluates to an infinite seq of nils!

(take 10 (range nil 0 nil))
=> (nil nil nil nil nil nil nil nil nil nil)

:boom:

(also raised for discussion on the clojurians slack)

Comments

tl;dr: not an issue. Similar discussions have been had before, e.g. https://ask.clojure.org/index.php/12903/why-does-this-work-in-cljs-but-doesnt-in-jvm-clojure with various links or https://ask.clojure.org/index.php/12051/apply-behaves-differently-in-clj-cljs-with-empty-argument or https://ask.clojure.org/index.php/12045/expected-difference-in-clj-cljs-behavior-with-apply-max - just the ones I found within 2 minutes and only on this website.

Answer 1

The behavior of non-numeric args passed to range is undefined.