lib.trivial: add neq function

[0x5a4]

Things done

I've added the neq function to lib.trivial, a higher order function for the != operator.

Its quite useful for constructing simple predicates, e.g. for filter

lib.filter (lib.neq "") ["a" "" "b"]
=> ["a" "b"]

In comparison, the same line without neq:

lib.filter (x: x != "") ["a" "" "b"]
=> ["a" "b"]

I personally prefer the first variant, though I can understand if this addition is seen as unnecessary. (I'm also just a huge fan of partially applied functions, so I might be biased here)

In general I feel like lib.trivial is missing a few functions for operators, though I think this is one of the more useful ones.

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[0x5a4]

after thinking about this some more, i feel like this is the kind of thing that the fairbarn principal thingy refers to...