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38 lines
839 B
Nix
38 lines
839 B
Nix
{ config, pkgs, ... }:
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with pkgs.lib;
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let
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failed = map (x: x.message) (filter (x: !x.assertion) config.assertions);
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in
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{
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options = {
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assertions = mkOption {
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default = [];
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example = [ { assertion = false; msg = "you can't enable this for that reason"; } ];
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merge = pkgs.lib.mergeListOption;
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description = ''
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This option allows modules to express conditions that must
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hold for the evaluation of the system configuration to
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succeed, along with associated error messages for the user.
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'';
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};
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};
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config = {
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# This option is evaluated always. Thus the assertions are checked as well. hacky!
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environment.systemPackages =
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if [] == failed then []
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else throw "\nFailed assertions:\n${concatStringsSep "\n" (map (x: "- ${x}") failed)}";
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};
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}
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