This removes some stale code that was a no-op for some time and adds
some docs/examples to help people with explicitly and consistently
choosing versions of some emacs packages (to help with problems
similar to #27083).
Also add a wrapper generator that allows adding the plugins back
conveniently and corresponding documentation in the package notes
section of the nixpkgs manual.
So that helper scripts can be easily sourced in interactive shell
configuration. `autojump` package was already present and had the same
requirements for findind a `share` folders, so I took an inspiration
there.
I beleive this is a better alternative to:
- https://github.com/NixOS/nixpkgs/pull/25080
- https://github.com/NixOS/nixpkgs/pull/27058
Replacing `$out/share/shell` with `$bin/share/fzf` was necessary to
prevent dependency loop in produced derivations.
This gives some basics on configuring Emacs within Nix. The
configuration is fairly long just to give a good idea of what’s going
on. I can trim out some of it if it’s not necessary. Note that there
is already a section for Emacs in the NixOS manual. However, this is
aimed at avoiding using modules altogether to make things easier for
non-NixOS users. This configuration should work on NixOS anyway,
however.
Fixes #24243
Fixes #19956
