22 lines
648 B
Nix
22 lines
648 B
Nix
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# Operations on attribute sets.
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with { inherit (builtins) head tail; };
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rec {
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inherit (builtins) attrNames listToAttrs hasAttr isAttrs;
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# Return an attribute from nested attribute sets. For instance ["x"
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# "y"] applied to some set e returns e.x.y, if it exists. The
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# default value is returned otherwise. !!! there is also
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# builtins.getAttr (is there a better name for this function?)
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getAttr = attrPath: default: e:
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let attr = head attrPath;
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in
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if attrPath == [] then e
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else if builtins ? hasAttr && hasAttr attr e
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then getAttr (tail attrPath) default (builtins.getAttr attr e)
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else default;
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}
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