Fix Haskell ormolu fixer

[eahlberg]

1. Fix ormolu fixer doesn't work out of the box #4593 by enabling ormolu's --stdin-input-file option by default.
2. Switch to the same design as other Haskell fixers (see Add better support for Haskell stack compiler tools #1851), which AFAIU is to improve support for stack. Note: I haven't been able to test this since I haven't found a way to make stack work on my setup (NixOS and cabal).

[w0rp]

@% may not be the current file at the time the linter runs, as this code could be executed from a different buffer. Instead get the filename using the a:buffer variable. ALE has a shorthand for this where you can use %s in the command string. See :help ale-command-format-strings.

Have a look at changelogs and make sure the --stdin-input-file argument is available in old enough ormolu versions. If it's not available in older versions, you can make this fixer function still compatible with older versions with the ale#semver functions and a version check. You can grep the codebase for other fixers that run version checks.

[eahlberg]

Sorry for being slow to respond but thanks for the feedback!

@% may not be the current file at the time the linter runs, as this code could be executed from a different buffer. Instead get the filename using the a:buffer variable. ALE has a shorthand for this where you can use %s in the command string. See :help ale-command-format-strings.

👍

Have a look at changelogs and make sure the --stdin-input-file argument is available in old enough ormolu versions. If it's not available in older versions, you can make this fixer function still compatible with older versions with the ale#semver functions and a version check. You can grep the codebase for other fixers that run version checks.

ormolu is a Haskell program which uses Haskell PVP which AFAIU means the ale#semver functions won't work. I couldn't find usage of PVP version checks in the codebase, but I guess one option would be to create a similar ale#pvp module. Does that sound reasonable or do you know of a better way to solve this?

[stale]

This pull request has been automatically marked as stale because it has not been updated recently. Make sure to write tests and document your changes. See :help ale-dev for information on writing tests.
If your pull request is good to merge, bother w0rp or another maintainer again, and get them to merge it.