Create an alpine image with GHC 8.10.7 + integer-gmp

[joe-warren-permutive]

I'm trying to run a project based on the latest stackage lts (currently 18.9, GHC 8.10.7).

While the alpine bindist has been intended to be an “integer-simple” build for a while, the release notes for 8.10.6 include:

Many packaging related fixes, including versioned ghc-pkg executables (#20087), and actually distributing GHC versions linked against the integer-simple big integer backend (#18967, #19953) on both Windows and Alpine Linux. Previous releases were still linked against the GMP library due to a misconfiguration of the builders.

So effectively 8.10.6 is the first release for which the alpine build has used the integer-simple backend.
This effectively doesn’t work with stack, because lots of stackage packages are configured to assume “integer-gmp”.
(It's possible to work around this, by configuring and pinning an "integer-simple" version of each package in the extra-deps, but this is a lot of overhead, and kinda defeats the point of using package sets)

While it might be possible to build ghc from source, on alpine, with the integer-gmp backend. I've been struggling to do this myself (due to a combination of linker errors, and slow build times within Docker).

[joe-warren-permutive]

It's possible that this (understandably) falls outside of the kind of work that you want to do in maintaining this repo.
If so, I'd appreciate pointers about where else to ask this?
I'm relatively invested in being able to run the latest stackage lts on alpine, but am personally finding it difficult to work out how to do this.

Cheers.

[nh2]

As a side info, I wanted to point out this which is going to come out soon and might be relevant/useful for Alpine:

• https://gitlab.haskell.org/ghc/ghc/-/merge_requests/6437 - Static alpine rebase
• https://gitlab.haskell.org/ghc/ghc/-/merge_requests/5147 - Introduce an alpine-based statically-linked binary distribution flavour

There is also ghc-bignum that might be relevant, a pure-Haskell replacement of integer-simple with BSD license: https://iohk.io/en/blog/posts/2020/07/28/improving-haskells-big-numbers-support/ I haven't used it myself yet though so I'm not sure how useful it'd be for this, or what the current state is.

---

What exactly do you mean by

lots of stackage packages are configured to assume “integer-gmp”

?

• Do you mean that some packages' code imports Haskell modules that are only present in integer-simple?
• Or do you mean packages like blaze-textual which has a Cabal flag integer-simple to "use integer-simple instead of integer-gmp", and that the musl based docker image should perhaps carry a stack config that enables the integer-simple flag for all such packages?

[joe-warren-permutive]

What exactly do you mean by "lots of stackage packages are configured to assume “integer-gmp”"

The latter:

Or do you mean packages like blaze-textual which has a Cabal flag integer-simple to "use integer-simple instead of integer-gmp", and that the musl based docker image should perhaps carry a stack config that enables the integer-simple flag for all such packages?

[snoyberg]

I'd be in favor of creating such an image, but I won't have time myself to try and build GHC with integer-gmp myself.