`(max "x" "y")` used to return "y", now it returns "x"

Question

Hello!

With cljs 1.12.42:

cljs.user=> (max "x" "y")
"y"
cljs.user=>

With cljs 1.12.134:

cljs.user=> (max "x" "y")
"x"
cljs.user=>

Probably related to CLJS-3425 and this commit which added NaN checks:

(defn ^number max
  "Returns the greatest of the nums."
  ([x] x)
  ([x y]
   (cond
     (NaN? x) x
     (NaN? y) y
     (> x y) x
     :else y))
  ([x y & more]
   (reduce max (cljs.core/max x y) more)))

But:

cljs.user=> (NaN? "x")
true
cljs.user=>

Hence the result.

Not sure what the expected result should be since min/max are only supposed to work with numbers but current behavior is surprising.

See also: https://github.com/jank-lang/clojure-test-suite/pull/839.

Answer 1

The docstring of max implies that it should be used for numbers.

Comments

Yes. Still don't understand the current behavior. Why not doing something like throwing an error?

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Because checking things can slow things down and in general you don't want this for numeric operators which should be fast

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ok, thank you!