[bug#49606] [PATCH wip-haskell v2] gnu: Add ghc-8.10.

[Lars-Dominik Braun]

Hi,

> AFAIK, ‘-next’ packages are usually unstable versions of the regular
> version, e.g., ‘emacs-next’ and ‘guile-next’.  ‘ghc-8.10’ is a stable
> release, so I am not sure if the ‘-next’ prefix is appropriate.
that is true, but I don’t see any other way to make

        guix environment --pure --ad-hoc ghc ghc-aeson -- ghci
        > import Data.Aeson

do “the right thing” by default. We could also argue that from
Guix’s point of view GHC 8.8/8.10 is (right now) unstable, because our
entire set of Haskell packages is built with GHC 8.6 (and thus untested
with higher versions of base). We also have python-next@3.9.2 on master
with (I think) exactly the same purpose. So, unless there’s any strong
objections I’ll be bold and rename GHC>8.6 to ghc-next, explaining
the situation in a comment.

> But seeing as there isn’t much interest in a
> Haskell update, applying to ‘master’ seems like a better idea.
I’m counting three people (John, you and me) interested in getting
Haskell back into shape, so let’s just do it :)

Cheers,
Lars