Enable support for developing with nix

[adithyaov]

Add a default.nix which

• can behave like a dev env when used by nix-shell
• has attributes with nix expressions that are generated by cabal2nix

[vrom911]

Hey @adithyaov . Thanks for the initiative.
We are not Nix users, so we are not the right people to maintain such kind of configs. Actually, we had the experience already here of having people contribute nix files to us, but it became obsolete with time. Then people were coming to us complaining about non-working configs. As we don't know how to fix it, how to maintain it, we just remove them after all, so the situation is not winning for either of the parts: we can not maintain it, so it is an additional burden on us; users are upset with outdated configs that are not working anymore; and the contributor feels sad as their work is being removed.

So unless we start using Nix ourselves to be able to keep it up to date, I don't see the nice way of having this feature, unfortunately. Especially, if it is even not tested on CI, so we are not aware of when it is broken.

[adithyaov]

Hi @vrom911,

Thank you for replying. The idea of nix is to have something reproducible and working. In my experience, I find nix very reliable.

Of course, one might need to update the nix file at times. The maintenance overhead might not be in the best interests of the maintainers and regular developers.

With that in mind, I believe the best thing to do is to close the corresponding PR, and if possible, keep this issue open for any future work related to nix.

This (closed) #525 PR serves as a good starting point to add nix to the project.