Fixes#692
The standard permits a user to access a constructor from a type stored inside
a record, but the Haskell implementation had a mistake which prevented this.
Specifically, the Haskell implementation was not normalizing the union type
as the standard specified before attempting to access the constructor, leading
to an unexpected type error.
This begins updates the filesystem layout for the tests to match
the new layout from the standard test suite (See:
https://github.com/dhall-lang/dhall-lang/pull/265)
This is still missing a part of the standard requirement, which is checking
parsing and import test results against an expected output (instead of
just checking that they succeed). I plan to add that in a subsequent
pull request. This is mainly to unblock other features that require using
the new standard layout.
The motivation for this change is:
* To catch build failures in downstream packages whenever we make a breaking
change to the `dhall` API
* To reduce the amount of work I need in order to cut a release for all of
these packages
* To better share Nix/CI-related logic between the projects
Note that I have not yet migrated `dhall-nix` in. I'm waiting for
https://github.com/dhall-lang/dhall-nix/issues/17 to be fixed since
`dhall-nix` is incompatible with later versions of `megaparsec` due to
`hnix`.
