Javascript backend emitted code that access global variable

[iacore]

If possible, please include complete self contained source files (for example by uploading to https://gist.github.com) that exhibit the issue in addition to quoting from them here. The smaller the example the better!

Steps to Reproduce

mod.idr:

main : IO ()
main = printLn (mod 3 4)

> idris2 mod.idr --cg javascript
     ____    __     _         ___
    /  _/___/ /____(_)____   |__ \
    / // __  / ___/ / ___/   __/ /     Version 0.5.1-676ca0dc0
  _/ // /_/ / /  / (__  )   / __/      https://www.idris-lang.org
 /___/\__,_/_/  /_/____/   /____/      Type :? for help

Welcome to Idris 2.  Enjoy yourself!
Main> :compile out2 main
File build/exec/out2 written

Expected Behavior

there should be let in front

  let r = a % b

Observed Behavior

In build/exec/out2:

// Euclidian Modulo
const _mod = (a,b) => {
  r = a % b
  return r < 0 ? (b > 0 ? r + b : r - b) : r
}

const _modBigInt = (a,b) => {
  r = a % b
  return r < 0n ? (b > 0n ? r + b : r - b) : r
}

[stefan-hoeck]

This is expected behavior. Idris, unlike JavaScript, uses euclidian modulo. See the discussion here: #1048 and #1480.

[iacore]

The problem is not about modulo. The problem is using r (global variable) without let.

[stefan-hoeck]

OK. Sorry about that. I'll submit a fix.

[iacore]

@stefan-hoeck don't use % at all.

~~The terrible language doesn't have % for BigInt.~~

https://tc39.es/ecma262/multipage/ecmascript-language-expressions.html#sec-applystringornumericbinaryoperator

Edit: I found it later in spec

https://tc39.es/ecma262/multipage/ecmascript-data-types-and-values.html#sec-numeric-types

[stefan-hoeck]

According to the tests we run, % works fine. So, according to your Edit: Can we use the operator or not? I'm afraid your messages are often rather cryptic...

[iacore]

We can, probably. It works in Node.JS and Firefox for me.

It's the ECMA standard for ~~JS~~ ECMAScript 2023 that's self-inconsistent.