GHC 8.4.3

[Timothy Sample]

Hi all,

Some of you may recall that I started work on updating all of our
Haskell packages to their LTS 12 versions, and making sure they all
build with GHC 8.4.3.  I think this work is ready to be included now (on
a WIP branch, at least).  The commits exist at
<https://gitlab.com/samplet/guix/tree/wip-haskell> under the
“wip-haskell” branch.  There are 258 commits, and they have been rebased
on master (although that was a few days ago, but it should be fine
because the Haskell packages have been relatively stable).  I figure
that 258 commits is too many for guix-patches, so I’m hoping that
someone (Ricardo?) can take them from the repo linked above.  There are
about 450 packages that need to be rebuilt.

Here are some notes that you might find interesting if you rely on our
Haskell infrastructure.

  • There are 21 failing packages.  They are agda, beast, corrode,
    git-annex, ghc-aws, ghc-gnuplot, ghc-haddock-test,
    ghc-hashable-bootstrap, ghc-indents, ghc-monadplus,
    ghc-nats-bootstrap, ghc-packedstring, ghc-regex, ghc-regex-tdfa-rc,
    ghc-statistics, ghc-vector-builder, ghc-wave, ghc-xmonad-contrib,
    raincat, rapicorn, and shellcheck.  Some of these are abandoned
    upstream, but most of them just need some extra attention.  I will
    look through them (especially git-annex), but I would like the
    stability of the build farm as I do it.  (Also, help wanted!)

  • The new Haskell no longer supports the “--allow-newer” flag, so it
    has to be worked around with phases and “substitute*”.  However, I
    have introduced a “#:cabal-revision” keyword that tells the build
    system to patch in newer revisions of the package’s Cabal file from
    Hackage.  This means that we can use this mechanism whenever
    upstream has updated the dependency constraints (which is the main
    reason we made so much use of “--allow-newer” in the first place).

  • I removed “ghc-mtl” since it is now included in GHC.

If you review the patches (thanks!) you might want to know:

  • I went through all of them carefully and I sincerely hope the error
    and typo count is low!  Also, most of them are machine generated, so
    those are probably fine.

  • There are a few more interesting commits that deserve special
    attention.  There are (minor) changes to the Stackage importer,
    there’s the “#:cabal-revision” stuff, and there are some
    old/unneeded packages that I deleted.

Let me know if there is anything I can do to make these changes easier
to work with.


-- Tim