4a524cf662
Note that ${} substitution doesn't work because of the "cannot refer
to other paths" constraint. The paranthesis are needed to enforce
right-first evaluation.
68 lines
2.6 KiB
Nix
68 lines
2.6 KiB
Nix
/* Impure default args for `pkgs/top-level/default.nix`. See that file
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for the meaning of each argument. */
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with builtins;
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let
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homeDir = builtins.getEnv "HOME";
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# Return ‘x’ if it evaluates, or ‘def’ if it throws an exception.
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try = x: def: let res = tryEval x; in if res.success then res.value else def;
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in
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{ # We combine legacy `system` and `platform` into `localSystem`, if
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# `localSystem` was not passed. Strictly speaking, this is pure desugar, but
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# it is most convient to do so before the impure `localSystem.system` default,
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# so we do it now.
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localSystem ? builtins.intersectAttrs { system = null; platform = null; } args
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, # These are needed only because nix's `--arg` command-line logic doesn't work
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# with unnamed parameters allowed by ...
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system ? localSystem.system
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, platform ? localSystem.platform
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, # Fallback: The contents of the configuration file found at $NIXPKGS_CONFIG or
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# $HOME/.config/nixpkgs/config.nix.
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config ? let
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configFile = getEnv "NIXPKGS_CONFIG";
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configFile2 = homeDir + "/.config/nixpkgs/config.nix";
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configFile3 = homeDir + "/.nixpkgs/config.nix"; # obsolete
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in
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if configFile != "" && pathExists configFile then import configFile
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else if homeDir != "" && pathExists configFile2 then import configFile2
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else if homeDir != "" && pathExists configFile3 then import configFile3
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else {}
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, # Overlays are used to extend Nixpkgs collection with additional
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# collections of packages. These collection of packages are part of the
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# fix-point made by Nixpkgs.
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overlays ? let
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dirPath = try (if pathExists <nixpkgs-overlays> then <nixpkgs-overlays> else "") "";
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dirHome = homeDir + "/.config/nixpkgs/overlays";
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dirCheck = dir: dir != "" && pathExists (dir + "/.");
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overlays = dir:
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let content = readDir dir; in
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map (n: import (dir + ("/" + n)))
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(builtins.filter (n: builtins.match ".*\.nix" n != null || pathExists (dir + ("/" + n + "/default.nix")))
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(attrNames content));
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in
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if dirPath != "" then
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overlays dirPath
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else if dirCheck dirHome then overlays dirHome
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else []
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, ...
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} @ args:
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# If `localSystem` was explicitly passed, legacy `system` and `platform` should
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# not be passed.
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assert args ? localSystem -> !(args ? system || args ? platform);
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import ./. (builtins.removeAttrs args [ "system" "platform" ] // {
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inherit config overlays;
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# Fallback: Assume we are building packages on the current (build, in GNU
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# Autotools parlance) system.
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localSystem = { system = builtins.currentSystem; } // localSystem;
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})
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