Please, provide wrapper with ability to respect the reproducible Nix envs that projects provide

[Anton-Latukha]

Subject of the issue

Currently, I am thinking is it right solution that all IDEs are currently required to provide their own custom Nix env loading mechanism and wrapper for the haskell-language-server-wrapper, because there is no support of Nix env in the HLS wrapper.

IDK. There is already support and docs of that in most IDEs. But to make a truly clean code refactoring of the ecosystem for the Nix env and NixOS case - they probably need to be accounted into the wrapper, at least as an option key for the wrapper, which maybe/probably needs to use by default on NixOS, as I said - because on NixOS Haskell projects needs to be built in project's Nix env, and if no Nix env provided - NixOS people need to create it by caba2nix, because there is no two-way support between NixOS system env & Cabal, shortly: Cabal works only in nix-shell on the NixOS, which means always load provided Nix env.

Your environment

• NixOS

Steps to reproduce

Download any Haskell project that provides Nix env. How to make HLS use provided reprocucible Nix env without a custom sidecars project?

Expected behaviour

HSL wrapper to provide an option to load the projects Nix env.

Actual behaviour

IDEs invent and maintain their own Nix env wrappers to wrap the HLS wrapper into them to load the projects Nix env and start HLS inside it.

[Anton-Latukha]

If you have a flashback - topic moved from #122.

[Anton-Latukha]

I started spitballing the PR: #490

Seems simple.

HLS and ghcid currently have problems loading HLS project in Nix env, at least HLS shell.nix and ghcid situation needs to be looked into. Currently, code is in pure draft mode, until something (me on Ubuntu, or utils loading HLS in Nix env) works.

You are free to start your own PR, or add your hacking into the current PR.

[michaelpj]

I think this is solved fairly well with direnv:

• Use lorri or similar to get information from the nix-shell to direnv
• Use a direnv support plugin in your editor (emacs has one, vscode has one) to get the right environment for the server launch.

Best of all, it's completely independent of us.

[michaelpj]

I also really don't think this is HLS's problem. We can't expect every executable under the sun to implement Nix support, rather you usually expect the user to set up the environment. And there are tools to help them with that (like direnv).

[fendor]

I agree, usage with lorri works well in my experience.

[ocharles]

One more happy lorri user. I haven't had to do anything special to get haskell-language-server working in any of my projects. I just let Emacs launch it, and use envrc-mode to make sure that Emacs respects my Lorri environment.

[Anton-Latukha]

I am actually one that forgot about existence of direnv configs.

Ok, I'm convinced at this point 8)

Thank you.