Format with Fourmolu

[ocharles]

@ryndubei Now that we've got multiple people working on this, I think it might be worth using a formatter, rather than having people faff around with the (somewhat esoteric) formatting I used when I started this project. At CircuitHub, we use the following fourmolu.yaml:

indentation: 2
comma-style: leading
import-export-style: diff-friendly
indent-wheres: true
record-brace-space: false
respectful: true
haddock-style: multi-line
newlines-between-decls: 2
fixities: []
single-constraint-parens: auto

What do you think? Shall we apply this here too? I also suggest we drop the package comments for now, though https://github.com/circuithub/ch-hs-imports does exist to automate this if we want it.

[ryndubei]

I'm in favour of having a formatter - this config looks good to me. I don't see a reason to remove package comments though, as they work fine with Fourmolu and I imagine they would be helpful in cases of switching out some package for another.

[ocharles]

Cool, let's add fourmolu and keep the comments then