Add dhall lint support for deprecating Optional/{fold,build}

[Gabriella439]

No description provided.

[sjakobi]

Awesome! :)

I suspect that these refactorings won't produce the desired results at least in the case of applied Optional/folds though. How about also matching on a fully applied Optional/fold then, and rewriting that to a merge-expression?

[Gabriella439]

@sjakobi: I'll postpone this until after the 1.29 release, because addressing your feedback is tricky

[sjakobi]

@sjakobi: I'll postpone this until after the 1.29 release, because addressing your feedback is tricky

Feel free to merge as-is then. We can still add the other refactoring at a later stage.

[sjakobi]

Ah, now I understand why my request was tricky to implement! :) Cheers!

[Gabriella439]

Yeah, the rewrite is depth-first, so the Optional/fold gets replaced before the rewrite has a chance to match on the larger saturated Optional/fold expression