Don't remove existential quantification (#339)

[imuli]

• also don't remove context from data declarations

Fixes: #339

[EncodePanda]

@jaspervdj I don't seem to have the rights to re-run the CI, could you possibly do that?

[EncodePanda]

@imuli do you want to pair up to push this PR forward?

[imuli]

I have limited personal bandwith at the moment, but I will attempt to find some. I can at least rebase onto the current main branch if that's helpful.

[imuli]

Looks like the CI on macOS is still having problems.

[EncodePanda]

I've just fixed mac cache. Can you rerun?

[EncodePanda]

By rerun I mean rebase one more time, please :)

[cdornan]

It would be awesome if we could get this patch released.

[EncodePanda]

@cdornan I've bumped the CI so the tests are passing now. I will evaluate the PR over the weekend and if all is good we will get it in.

[EncodePanda]

@imuli could we add

case60 :: Assertion
case60 = assertSnippet (step defaultConfig)
    [ "data Foo = forall a . Bar a" ]
    [ "data Foo = forall a. Bar a" ]

for completeness?

[EncodePanda]

please update the comment to https://github.com/jaspervdj/haskell/issues/339

[EncodePanda]

@imuli this is amazing work! thank you so much for the contribution!

Please add the missing test case60 (just copy-paste from the comment) and update the link to the issue in the comment.

One more time, thank so much for this :)

[EncodePanda]

LTGM