Implement scalafmt

[easel]

Resolves #1206 and replaces #1731

[codecov-io]

Codecov Report

Merging #2546 into master will not change coverage.
The diff coverage is 0%.

@@           Coverage Diff           @@
##           master    #2546   +/-   ##
=======================================
  Coverage   95.17%   95.17%           
=======================================
  Files         359      359           
  Lines        6555     6555           
  Branches      273      273           
=======================================
  Hits         6239     6239           
  Misses        316      316

Impacted Files	Coverage Δ
js/src/main/scala/cats/js/instances/future.scala	0% <0%> (ø)	⬆️

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[easel]

I don't think the codecov/patch failure is relevant. There's perhaps some additions to the CONTRIBUTING.md or something that should go along with this. Any thoughts?

[LukaJCB]

Okay, someone has to start the bikeshedding, so here goes:

I'd like to see

align=none
maxColumn = 120

The rest of the default settings I think are good :)

[easel]

I've pushed another commit applying @LukaJCB's bikeshed suggestions. Both seem reasonable. I like alignment, but for a larger project it will create diff noise that may be less than desirable. 120 columns is a reasonable max in the modern world, although I'd say the "style guide" should recommend 80.

[ceedubs]

Awesome, @easel! Thanks a bunch.

This looks good to me, but... how is it such a small changeset? I would expect it to touch a ton of lines. Is it actually running on all of the modules?

[ceedubs]

The only changes are in the jvm/js projects which makes me think that maybe our JVM/JS cross-building setup is throwing off scalafmt.

[easel]

@ceedubs Thats an interesting possibility, the cats cross build stuff is definitely beyond the basics. From my perspective if we can bikeshed out the settings it would be best to just get this merged and then work on applying it to any missing submodules as we can. That way the settings are documented and people can use them on their own.

[ceedubs]

As I mentioned in a comment, I think that the JVM/JS cross-building is causing most modules to not be picked up, but this still seems like strictly an improvement, so 👍 from me.

[joan38]

Why this comment // default settings ?

[kailuowang]

shall we close this since #2562 is merged?