`stack` support?

Hi,
thank you for this!

It was very simple to use it in a minimal repro : https://github.com/ocramz/alpine-ghc-static

For a larger project with complex upstream dependencies, I am forced to compile with `stack` which is however not provided in this image.

Would it be possible to add `stack` installation to the Docker images?

I see stack is available for Alpine:

https://pkgs.alpinelinux.org/packages?name=stack&branch=edge&repo=&arch=x86_64&origin=&flagged=&maintainer=

Thank you!