There are fixed size of known VCS, implement Representable container.

[phadej]

I.e. container such lookup :: RepoType -> VCS a -> a would be total.

One would need to split OtherRepoType String out of RepoType, into separate type.

There're handful of errors to be removed by this refactor.

I think this is newcomer friendly refactoring.

---

One example of this "issue", is e.g. miss-typing type in source-repository-package:

% cabal build      
cabal: (SourceRepo {repoKind = RepoThis, repoType = Just (OtherRepoType
"gitt"), repoLocation = Just "https://github.com/phadej/tree-diff.git",
repoModule = Nothing, repoBranch = Nothing, repoTag = Just "123", repoSubdir =
Nothing},SourceRepoRepoTypeUnsupported (OtherRepoType "gitt"))

Technically, we don't need to accept unknown RepoTypes to begin with in the cabal.project parser. Thus there's small argument from splitting RepoType into Enum part, and Either String like wrapper.

[v0d1ch]

@phadej how would you like this Either String like wrapper to look?
I am asking just to make sure I do exactly the thing you wanted.

[phadej]

Currently we have

data RepoType = Darcs | Git | SVN | CVS
              | Mercurial | GnuArch | Bazaar | Monotone
              | OtherRepoType String

After we could have

data KnownRepoType = Darcs | Git | SVN | CVS
                   | Mercurial | GnuArch | Bazaar | Monotone

data RepoType = KnownRepoType KnownRepoType
              | OtherRepoType String

[v0d1ch]

Hey @phadej I made the changes and blindly fixed the compiler errors in code and tests.
Here is the diff master...v0d1ch:6432-implement-Representable-container

There is one test that keeps failing and I need some help fixing it:

  Distribution.Utils.Structured
    VersionRange:                                                                         OK
    SPDX.License:                                                                         OK
    LocalBuildInfo:                                                                       FAIL
      tests/UnitTests/Distribution/Utils/Structured.hs:26:
      expected: 2b983b5312a676b13edb7b476c2fd11e
       but got: e2909c4dccc1d2dea065d96aa3d0d915

[phadej]

The Structured tests fails for a reason. We indeed change type definitions. The solution is simply copy the new hash into the test (you need to split it in half and add 0x for hex numbers).

[phadej]

The patch looks fine. I'll comment more when you make a PR. Thanks for picking this issue!