Stop using ppa:hvr/ghc

[Bodigrim]

ppa:hvr/ghc is abandoned and no longer provides packages neither for new Ubuntus nor for new GHCs. This week GHA started to alias ubuntu-latest to ubuntu-22.04, rendering ppa:hvr/ghc just a burden, slowing down things. What's the reason to use two sources of bindists? Seems ghcup has the same coverage for Ubuntu.

[andreasabel]

The ppa:hvr/ghc repo has GHC 7.x which isn't on ghcup, and it can be used with ubuntu-20.04.
I agree that the default installation method should be ghcup.
But the code enabling installation via ppa:hvr/ghc is already there, so what would be the great benefit of removing it?

[Bodigrim]

The ppa:hvr/ghc repo has GHC 7.x which isn't on ghcup, and it can be used with ubuntu-20.04.

That's true in general, but this action does not support GHC < 7.10 anyway: https://github.com/haskell/actions/tree/main/setup#version-support.

[andreasabel]

GHCup only supports <= 8.2 on paper, but not in reality, at least not on ubuntu-22.04, see: haskell/unix#266 (comment)

[andreasabel]

GHCup only supports <= 8.2 on paper, but not in reality, at least not on ubuntu-22.04, see: haskell/unix#266 (comment)

According to @hasufell, it does, but on ubuntu-22.04 one needs to install extra libraries: haskell/unix#266 (comment)

[andreasabel]

When @phadej drops GHC 7.x, we could take the bold step and drop GHC 7.x altogether. Then we can simplify this action...

[phadej]

How is this predicated on what I do? I don't use haskell/actions, so I don't mind what's done here.

[andreasabel]

Maybe Swedish consensus culture. Feels more right to abandon GHC 7 when Haskell-CI does so as well.

[Bodigrim]

I don't quite get what prevents us from simplifying this action right now. The action itself supports only GHC >= 7.10 and since #136 all such GHCs can be installed via ghcup on all Ubuntu runners. How ppa:hvr/ghc makes anything better?

The situation with haskell-ci is different: it does support GHC < 7.10, so it has reasons to stick to ppa:hvr/ghc for a bit longer.

Upd.: As #138 demonstrates, I've been wrong: this action can install GHC < 7.10 if asked directly, even while documentation says otherwise.