Commit f993f8a1 authored by figsoda's avatar figsoda
Browse files

lib/attrsets: add concatMapAttrs

parent 4536ebad

lib/attrsets.nix

+20 −1
Original line number Diff line number Diff line
@@ -3,7 +3,7 @@ 


let

  inherit (builtins) head tail length;

  inherit (lib.trivial) id;

  inherit (lib.trivial) flip id mergeAttrs pipe;

  inherit (lib.strings) concatStringsSep concatMapStringsSep escapeNixIdentifier sanitizeDerivationName;

  inherit (lib.lists) foldr foldl' concatMap concatLists elemAt all partition groupBy take foldl;

in
@@ -77,6 +77,25 @@ rec { 
    let errorMsg = "cannot find attribute `" + concatStringsSep "." attrPath + "'";

    in attrByPath attrPath (abort errorMsg);



  /* Map each attribute in the given set and merge them into a new attribute set.



     Type:

       concatMapAttrs ::

         (String -> a -> AttrSet)

         -> AttrSet

         -> AttrSet



     Example:

       concatMapAttrs

         (name: value: {

           ${name} = value;

           ${name + value} = value;

         })

         { x = "a"; y = "b"; }

       => { x = "a"; xa = "a"; y = "b"; yb = "b"; }

  */

  concatMapAttrs = f: flip pipe [ (mapAttrs f) attrValues (foldl' mergeAttrs { }) ];





  /* Update or set specific paths of an attribute set.

lib/default.nix

+1 −1
Original line number Diff line number Diff line
@@ -78,7 +78,7 @@ let 
    inherit (self.attrsets) attrByPath hasAttrByPath setAttrByPath

      getAttrFromPath attrVals attrValues getAttrs catAttrs filterAttrs

      filterAttrsRecursive foldAttrs collect nameValuePair mapAttrs

      mapAttrs' mapAttrsToList mapAttrsRecursive mapAttrsRecursiveCond

      mapAttrs' mapAttrsToList concatMapAttrs mapAttrsRecursive mapAttrsRecursiveCond

      genAttrs isDerivation toDerivation optionalAttrs

      zipAttrsWithNames zipAttrsWith zipAttrs recursiveUpdateUntil

      recursiveUpdate matchAttrs overrideExisting showAttrPath getOutput getBin

lib/tests/misc.nix

+17 −0
Original line number Diff line number Diff line
@@ -478,6 +478,23 @@ runTests { 


# ATTRSETS



  testConcatMapAttrs = {

    expr = concatMapAttrs

      (name: value: {

        ${name} = value;

        ${name + value} = value;

      })

      {

        foo = "bar";

        foobar = "baz";

      };

    expected = {

      foo = "bar";

      foobar = "baz";

      foobarbaz = "baz";

    };

  };



  # code from the example

  testRecursiveUpdateUntil = {

    expr = recursiveUpdateUntil (path: l: r: path == ["foo"]) {