Provide Nix shell environment

[koslambrou]

What is your idea? Provide a use case.

When wanting to develop on Kupo, I would be nice to have a shell.nix file enabling a development environment using nix-shell (or nix develop is using flakes). Could use haskell.nix.

Why is it a good idea?

Because just running nix-shell and having all the development environment setup is a good idea.

What is the current alternative and why is it not good enough?

Currentl alternative is installing dependencies ourselves and making sure we use the correct versions (GHC, cabal, haskell-language-server, etc.)

[KtorZ]

Current alternative is installing dependencies ourselves

I like this alternative to be honest 😶 ...

More seriously, I am generally quite opposed to Nix for deployment and package management in projects because it has never solved an actual problem for me -- yet has always added complexity and frustration. However, I am open to the idea of using Nix for provisioning environments. So a shell.nix that fulfill this role could be nice.

I have seldom used haskell.nix (only for producing static binaries) and it's not something I enjoy doing as I am not a Nix user. I don't mind a good old system-level installation. Hence, if you're willing to provide a PR with a shell.nix that can be used to provision an environment, I'll review it and see about merging it.

Having said that:

• It should not require generating or re-generating some random lock files. This is a nightmare to maintain down the line then.
• It should not use Nix to fetch Haskell dependencies; I still want plain cabal to handle the Haskell build. So I am fine with using Nix to provision the dev environment, but nothing more.

Perhaps something worth looking at is what Moritz has been up to with: https://github.com/input-output-hk/devx. I've been playing around that a bit but put that on hold for now. Yet I think he's doing exactly that.