Using pkgs.lib on the spine of module evaluation is problematic because the pkgs argument depends on the result of module evaluation. To prevent an infinite recursion, pkgs and some of the modules are evaluated twice, which is inefficient. Using ‘with lib’ prevents this problem.
78 lines
2 KiB
Nix
78 lines
2 KiB
Nix
{ config, lib, pkgs, ... }:
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with lib;
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let
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isConfig = x:
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builtins.isAttrs x || builtins.isFunction x;
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optCall = f: x:
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if builtins.isFunction f
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then f x
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else f;
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mergeConfig = lhs_: rhs_:
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let
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lhs = optCall lhs_ { inherit pkgs; };
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rhs = optCall rhs_ { inherit pkgs; };
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in
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lhs // rhs //
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optionalAttrs (lhs ? packageOverrides) {
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packageOverrides = pkgs:
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optCall lhs.packageOverrides pkgs //
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optCall (attrByPath ["packageOverrides"] ({}) rhs) pkgs;
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};
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configType = mkOptionType {
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name = "nixpkgs config";
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check = traceValIfNot isConfig;
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merge = args: fold (def: mergeConfig def.value) {};
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};
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in
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{
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options = {
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nixpkgs.config = mkOption {
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default = {};
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example = literalExample
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''
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{ firefox.enableGeckoMediaPlayer = true;
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packageOverrides = pkgs: {
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firefox60Pkgs = pkgs.firefox60Pkgs.override {
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enableOfficialBranding = true;
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};
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};
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}
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'';
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type = configType;
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description = ''
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The configuration of the Nix Packages collection. (For
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details, see the Nixpkgs documentation.) It allows you to set
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package configuration options, and to override packages
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globally through the <varname>packageOverrides</varname>
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option. The latter is a function that takes as an argument
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the <emphasis>original</emphasis> Nixpkgs, and must evaluate
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to a set of new or overridden packages.
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'';
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};
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nixpkgs.system = mkOption {
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type = types.str;
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description = ''
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Specifies the Nix platform type for which NixOS should be built.
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If unset, it defaults to the platform type of your host system
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(<literal>${builtins.currentSystem}</literal>).
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Specifying this option is useful when doing distributed
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multi-platform deployment, or when building virtual machines.
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'';
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};
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};
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config = {
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nixpkgs.system = mkDefault pkgs.stdenv.system;
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};
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}
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