haskell-template Add nix shell banner

Entering nix develop should print a welcome message similar to how https://github.com/yusdacra/rust-nix-templater does

May 06 '22 21:05 srid

If we can do this in a general way (abstracted way as an external repo to be used as a flake input, with minimal Nix stub) that would be ideal. cc @yusdacra

May 17 '22 08:05 srid

The devshell message there comes from https://github.com/numtide/devshell, which is a lightweight devshell with nice features. haskellPackages would need to use that for a devshell message. But haskell-template could probably just use devshell and set up a shellHook that sources the haskellPackages shell and add a commands using devshell configuration.

May 17 '22 09:05 90-008

@yusdacra Oh, I hadn't realized it came from numtide/devshell. Thanks.

Also: https://github.com/numtide/devshell/pull/6#issuecomment-1129029017

May 17 '22 15:05 srid

Done in https://github.com/srid/haskell-template/pull/72

Dec 19 '22 14:12 srid