Re-enable dhall

[ysangkok]

Checklist for adding a package:

• Meaningful commit message, eg add my-cool-package (please don't mention the yaml file)

• Package is already added to nightly (if possible)

• On your machine, in a new directory, you have successfully run the following set of commands (replacing $package and $version with the name and version of the package you want to add to Stackage LTS):

  stack unpack $package-$version
  cd $package-$version
  stack init --resolver lts
  stack --resolver lts build --haddock --test --bench --no-run-benchmarks
  

or using the verify-package script:

  verify-package $package lts

Now that

• Fix TyVar BndrVis dhall-lang/dhall-haskell#2622

is released to hackage as dhall-1.42.2, we can add dhall back to the LTS.
Sadly the other packages are not compatible yet, as far as I can see.

[mihaimaruseac]

Thank you

[mmhat]

Nice! Thank you @ysangkok @mihaimaruseac

[mihaimaruseac]

special-values (Grandfathered dependencies, Library and exe bounds failures) (not present) depended on by:

• dhall-1.42.2 (< 0.2). Gabriella Gonzalez GenuineGabriella@gmail.com @Gabriella439. Used by: test-suite

Will disable tests on LTS until we can add special-values

[ysangkok]

Pinged the maintainer on

• bytestring-0.12 not supported minad/special-values#5

In a week I will ask the trustees to bump.

[ysangkok]

@mihaimaruseac I just noticed that while special-values isn't getting bumped on the repo, it has had a compatible revision since December. So I believe it could get added.

[mihaimaruseac]

Oh, that's awesome!