zsh: add support for prezto configuration framework

[NickHu]

This commit adds support for prezto, an alternative to oh-my-zsh. Currently it depends on NixOS/nixpkgs#59134 to some extent (this pull request actually makes it so that $HOME/.zpreztorc is sourced).

[rycee]

Thanks for the contribution! I'm a bit worried about the size of this, though. Maintaining this will be a large job. And I'm worried about having two completely separate configuration frameworks in the same HM module.

If it's added then perhaps could have something simpler like

prezto = {
  settings = mkOption { type = types.attrsOf types.str; … };
  load = mkOption { type = types.attrsOf types.str; … };
  moduleConfig = mkOption { type = types.attrsOf (types.attrsOf types.str); … };
};

so that a configuration could be along the lines of

{
  prezto = {
    settings.case-sensitive = true;
    load = {
      pmodule-dirs = "$HOME/.zprezto-contrib";
    };
    module = {
      prompt.pwd-length = "long";
    };
  };
}

But I usually excuse myself when it comes to zsh module changes so I'll defer to the opinion of the zsh expert @uvNikita 🙂

[NickHu]

The reason for its size is so that everything can be configured from home-manager; I'm not sure that it should require much maintenance.

[teto]

Seems like there is some overlap between these ZSH frameworks and nix. There are settings for python env, more plugins, ruby, ssh identities. IMHO, the most value is made of nix is when settings are redundant or interdependant between software. This seems like it can remain selfcontained so why not just copy the configuration files ?

[NickHu]

@teto Yes, there is some overlap. The main advantage of these frameworks is that they're able to configure various plugins with minimal setup; nobody has bothered to write a nix-centric zsh plugin manager, so the next best thing is to co-opt an existing one in this way (as home-manager already does with oh-my-zsh).

@rycee It's been a year now and I've taken to patching home-manager to include this every time I update, so I would really like some incarnation of this to be merged. I think I was right in saying that it's effectively no-maintenance (the patch has applied cleanly every time), so how would you feel about merging now? Perhaps a neat way of splitting it up is to put most of the implementation in its own file (say something like modules/programs/zsh/prezto.nix) and using the import mechanism in the main zsh nix expression. I doubt the implementation would ever need to be changed, and I'm happy to take on responsibility for updating it if it ever does.

[anna328p]

I am also very interested in seeing this merged. I am currently using NickHu's fork of home-manager, which is understandably behind by many commits

[NickHu]

I've moved the prezto stuff to its own file to keep zsh.nix a bit slimmer; like I said before, prezto has a very very stable interface and this patch has applied cleanly since I wrote it over a year ago. If there are no objections then I'll add myself to the codeowners and merge this in.

[rycee]

Added a few comments but since I don't use zsh I can't review properly. If you don't agree with the comments then feel free to merge.