This is something that I struggle with. I know how to find top-level packages like git or cowsay. But what about utilities under nested paths? I always spend ages digging through the nixpkgs source code to try to find utilities to use in my nix expressions.

Today I want to use buildRustPackage. It’s defined here, and is propagated here. But how do I access it given a pkgs variable? I have no idea!

https://search.nixos.org/packages is no help

nix search nixpkgs doesn’t find it

I think I need to search by attribute name, not by derivation name. But I don’t know how to do that.

  •  hallettj   ( @hallettj@beehaw.org ) OPEnglish
    1•1 year ago

    After some more digging I think I figured it out.

    I was trying to use nix repl nixpkgs to interactively query packages. But I forgot that that command loads the flake, not the package set. You have to prefix everything with legacyPackages.x86_64-linux. to access packages in this environment. I got better results running nix repl followed by :l angle-bracket nixpkgs angle-bracket. (Btw the repl tells me how many variables have been loaded. Is there a way to list them? That would be helpful.) (Edit: nix repl nixpkgs#legacyPackages.x86_64-linux also works)

    I eventually found https://github.com/NixOS/nixpkgs/blob/35d87899f7c8f6fad50447301465d51b5dd87753/doc/languages-frameworks/rust.section.md?plain=1#L18 which tells me that what I want is pkgs.rustPlatform.buildRustPackage

    I would still like a way to search for nested attributes.