Build REST with -Werror -Wall

[facundominguez]

Same as ucsd-progsys/liquid-fixpoint#538.

[ConnorBaker]

I'd love to take this on!

On my fork I just finished refactoring the tests and moving to tasty, and I'm building with -Wall -Wno-name-shadowing -Werror (https://github.com/ConnorBaker/rest/blob/master/rest-rewrite.cabal#L20). I can re-enable the warning for name shadowing and fix any issues that may arise.

On a different note, ListT is deprecated (https://downloads.haskell.org/~ghc/9.0.1/docs/html/libraries/transformers-0.5.6.2/Control-Monad-Trans-List.html) and should be removed from the project (perhaps this should be another issue, although it does cause deprecation warnings).

Thankfully, it's only used a few times in Rest.hs (e.g., https://github.com/zgrannan/rest/blob/master/src/Language/REST/Rest.hs#L124), so it should be easy to remove ... given that the person doing the refactoring understands what's happening! I spent the better part of five hours this weekend trying to feel my way through the types and move away from that package, to no avail.

Any tips would be appreciated!

[zgrannan]

@ConnorBaker I've removed the deprecated ListT from Control.Monad.Trans and replaced it with a custom one, in case you're still interested in merging your branch.

Actually looking at your branch I see you have already replaced it with List-T, either way is probably fine :)

But it would be nice to get your changes merged in! It would be nice to be using a real test framework.