(reposted since I sent this to the wrong channel) Working on the cljs.math thing, I’m encountering a couple of cases where `-0.0` is significant. The IEEE-754 standard represents `0.0` as `0x0000000000000000`, and `-0.0` as `0x8000000000000000`. In Clojure, I can use these easily:

user=> -0.0
-0.0
user=> (str -0.0)
"-0.0"

> -0.0
-0
> "" + -0.0
'0'
> let z = -0.0
undefined
> z
-0

cljs.user=> -0.0
0
cljs.user=> (str -0.0)
"0"

cljs.user=> (def z -0.0)
#'cljs.user/z
cljs.user=> (let [buffer (js/ArrayBuffer. 8)
                  d (js/Float64Array. buffer)
                  b (js/Uint8Array. buffer)]
              (aset d 0 z)
              (str b))
"0,0,0,0,0,0,0,128"

hm. it seems to be due to .toString

> let n = -0
undefined
> n.toString()
'0'

(tested this in the browser but i'm guessing it's the same in node)

so toString drops the sign

it looks like showing the sign of zero in the JS REPL is a semi-recent update, since this article claims the same happens in Node.js: https://2ality.com/2012/03/signedzero.html

> let n = -0
undefined
> n.toLocaleString()
'-0'

probably dicey to change the way we stringify nums

> hm. it seems to be due to `.toString` I agree, since the node repl (or my version of node anyway, which is v12.18.3) displays -0 for the value, but not when it’s converted to a string. I appreciate finding the difference for .toLocaleString! I wouldn’t have thought to look for that.

I don't think we could use .toLocaleString since it's not round trippable, and I think people use things like pr-str to print out valid EDN

> let n = 10000
undefined
> n.toLocaleString()
'10,000'
> 10,000 // this will be parsed as the expression 10 <comma operator> 0
0