commit 341ac85644e93f145277be93db2a732ae3409249 · pyrox.dev/nixpkgs

+20
lib/attrsets.nix
···

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           listToAttrs (concatMap (name: let v = set.${name}; in if pred name v then [(nameValuePair name v)] else []) (attrNames set));

     

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         /* Filter an attribute set recursivelly by removing all attributes for

     

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            which the given predicate return false.

     

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            Example:

     

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              filterAttrsRecursive (n: v: v != null) { foo = { bar = null; }; }

     

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              => { foo = {}; }

     

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         */

     

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         filterAttrsRecursive = pred: set:

     

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           listToAttrs (

     

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             concatMap (name:

     

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               let v = set.${name}; in

     

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               if pred name v then [

     

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                 (nameValuePair name (

     

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                   if isAttrs v then filterAttrsRecursive pred v

     

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                   else v

     

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                 ))

     

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               ] else []

     

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             ) (attrNames set)

     

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           );

     

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       +
       

     

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         /* foldAttrs: apply fold functions to values grouped by key. Eg accumulate values as list:

     

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            foldAttrs (n: a: [n] ++ a) [] [{ a = 2; } { a = 3; }]

     

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            => { a = [ 2 3 ]; }