Add fourmolu to nix flake as a convenient script

[goodlyrottenapple]

Partially addresses #3236

[github-actions]

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test/regression-wasm/test-memory.sh	-0.000018	0

[jberthold]

Great, this can be very handy.
However, somehow it fails on my machine, possibly due to missing/wrong locale. I am getting around 25 errors like this:

jost@freshcode-1:~/work/RV/code/haskell-backend$ nix run .#format ./kore/src/Kore/Attribute/Smtlib/Smtlib.hs
warning: Git tree '/home/jost/work/RV/code/haskell-backend' is dirty
Loaded config from: /home/jost/work/RV/code/haskell-backend/fourmolu.yaml
fourmolu: ./kore/src/Kore/Attribute/Smtlib/Smtlib.hs: hGetContents: invalid argument (invalid byte sequence)

Quite possibly this is because of unicode characters in the comments. Smtlib.hs has a comment containing ≪S-expression≫, for instance.

Another kind of error is this, I am getting it 7 times:

warning: Git tree '/home/jost/work/RV/code/haskell-backend' is dirty
Loaded config from: /home/jost/work/RV/code/haskell-backend/fourmolu.yaml
AST of input and AST of formatted code differ.
  at kore/src/Debug.hs:(418,5)-(419,71)
Please, consider reporting the bug.

No idea about this one.

[goodlyrottenapple]

@jberthold can you try now? I've seen this unicode error before and it is to do with locales indeed.. Tried adding a fix to the script. As to the second error, that should be gone with formolu 0.4, which i switched to now

[goodlyrottenapple]

Still cannot get rid of this old nix-build because running the unit tests via nix flake segfaults randomly :/

[goodlyrottenapple]

switched to the stable 22.05 branch for all the utilities like fourmolu, eventlog2html, etc. as well as cabal/stack in the dev shell

[goodlyrottenapple]

this should hopefully address the unicode issue @jberthold

[jberthold]

👍 works like a charm now, thx for fixing the locale!