Ale: Add support for sass

[andrewminer]

I see that there is already support for a variety of CSS / SASS linters, but I can't find anything which actually validates the validity of the SCSS code itself. For example, even with the various sass linters installed, the following wouldn't trigger any errors, even though the $font-foo variable is undefined and causes a SASS parsing error:

body {
    font-family: $font-foo;
}

The SASS executable does have a --check option to only validate (no emitting CSS), so I would expect (from what I can tell) that it shouldn't be a difficult integration.

[w0rp]

... I would expect (from what I can tell) that it shouldn't be a difficult integration.

Famous last words.

[dakom]

Would this be possible via the LanguageServer support here? https://github.com/Microsoft/vscode-css-languageservice

Would that bring auto-completion too?

[realestninja]

How exactly do I enable linting for sass files?

[neersighted]

All supported linters are enabled by default, if installed. Check :help ale-sass for more details on what is supported.

GitHub issues is not really the proper place for tech support. Feel free to hop on gitter to get help with configuring ALE, or ask a question on Stack Exchange if your problem is more with Sass linters in general.

[realestninja]

Thanks for your quick response. I checked again today and noticed that 6days ago there was a commit that made my settings work. I just had to update my ALE. That commit might solve this issue in general.

PS: Great Plugin!