In reply to @wizardlink:matrix.org

Hello there! A quick and maybe dumb question...

I am currently working on my home-manager configuration and decided to make my scripts into .nix files that evaluate strings (for interpolating packages). Now, if I do

{
  # ...
  text = import ./my-script.nix;
}

It yields an error, which is very non-descriptive... But:

{
  # ...
  text = import ./my-script.nix { pkgs = pkgs; };
}

Does not errors and the function is evaluated? I thought that parameters got passed down kind of like imports does, but it isn't the case... Can someone explain me better how functions are evaluated in the case of an import?

Thanks in advance!

imports is actually a nixpkgs/nixos specific thing, it calls the "modules" (really functions) with a bunch of pre-defined arguments (see e.g. nixpkgs/lib/modules.nix if curious).

import on the other hand is a Nix keyword that parses and loads the expression from some path, and the attrSet it takes here (in your case { pkgs = pkgs; } is an argument passed to the function found in ./my-script.nix.

the start of your ./my-script.nix file likely looks something like this:

{ pkgs }:

Here, { pkgs }: is actually an anonymous function taking an attrSet with an attribute called pkgs.

In reply to @aos1:matrix.org
What are the odds that we're both answering this question around the same time haha. Your answer is more thorough cafkafk thanks. I do want to add some links in case it's helpful: https://nix.dev/manual/nix/2.18/language/builtins.html?highlight=import#builtins-import and https://nixos.org/manual/nixos/stable/#sec-writing-modules

ohh also, turns out import isn't technically a keyword, but a builtin 🙃

nix-repl> import = x: x + 1

nix-repl> import 10
11

In reply to@cafkafk:gitter.im

ohh also, turns out import isn't technically a keyword, but a builtin 🙃

nix-repl> import = x: x + 1

nix-repl> import 10
11

In reply to @cafkafk:gitter.im

ohh also, turns out import isn't technically a keyword, but a builtin 🙃

nix-repl> import = x: x + 1

nix-repl> import 10
11

arch = builtins.getAttr stdenvNoCC.hostPlatform.system {
  x86_64-linux = "x64";
  x86-linux = "x86";
};

vs

arch =
  {
    x86_64-linux = "x64";
    x86-linux = "x86";
  }
  ."${stdenvNoCC.hostPlatform.system}";