Add support for NumericUnderscores extensions from CLI/config

[friedbrice]

Closes #1434

[friedbrice]

@ndmitchell Is there a different way you'd like me to approach this problem? I'm happy to rework this.

[googleson78]

I think the toList here is redundant - you've already called toList inside moduleExtensions, right?

[friedbrice]

Thanks, @googleson78! I'll start working on a patch.

[ndmitchell]

Sorry it took me so disastrously long to get to this diff - it feel off my radar. I updated the merge conflicts, but didn't test after (did it in the github UI).

I can see how this would apply to people using the API, but as far as I can tell, this won't have any impact on the command line users? Or are you expecting that this will be used through the Haskell IDE?

[friedbrice]

@ndmitchell it works using our .hlint.yaml file. If it doesn't work for CLI uses, then that's an oversight on my part that I need to fix.

Edit to add: Here's a snippet of our .hlint.yaml, and it works as intended.

- arguments:
  - -XQuasiQuotes
  - -XTypeApplications
  - -XNumericUnderscores
  - -XNoForeignFunctionInterface
  - -XOverloadedRecordDot

[friedbrice]

Sorry I let this sit for so long. Thank y'all.

[parsonsmatt]

@ndmitchell anything we can do to get this ready to merge?