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author | Graham Christensen <graham@grahamc.com> | 2018-10-12 16:51:05 -0400 |
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committer | Graham Christensen <graham@grahamc.com> | 2018-10-12 16:54:34 -0400 |
commit | c100a456b1da162ea010e5880cded268aa68cec6 (patch) | |
tree | 5743ff631f1509055544f0c0d99d99bb294bd5a2 /doc/functions | |
parent | 77140a9075ea651c060fcb91a7a5da832e3a1e68 (diff) |
nixpkgs docs: document recursivelyUpdateUntil
Diffstat (limited to 'doc/functions')
-rw-r--r-- | doc/functions/library/attrsets.xml | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/doc/functions/library/attrsets.xml b/doc/functions/library/attrsets.xml index a719b7958458..a6fa2ea0e295 100644 --- a/doc/functions/library/attrsets.xml +++ b/doc/functions/library/attrsets.xml @@ -1563,4 +1563,112 @@ lib.attrsets.zipAttrs ]]></programlisting> </example> </section> + + <section xml:id="function-library-lib.attrsets.recursiveUpdateUntil"> + <title><function>lib.attrsets.recursiveUpdateUntil</function></title> + + <subtitle><literal>recursiveUpdateUntil :: ( [ String ] -> AttrSet -> AttrSet -> Bool ) -> AttrSet -> AttrSet -> AttrSet</literal> + </subtitle> + + <xi:include href="./locations.xml" xpointer="lib.attrsets.recursiveUpdateUntil" /> + + <para> + Does the same as the update operator <literal>//</literal> except that + attributes are merged until the given predicate is verified. The predicate + should accept 3 arguments which are the path to reach the attribute, a part + of the first attribute set and a part of the second attribute set. When the + predicate is verified, the value of the first attribute set is replaced by + the value of the second attribute set. + </para> + + <variablelist> + <varlistentry> + <term> + <varname>pred</varname> + </term> + <listitem> + <para> + <literal>[ String ] -> AttrSet -> AttrSet -> Bool</literal> + </para> + <variablelist> + <varlistentry> + <term> + <varname>path</varname> + </term> + <listitem> + <para> + The path to the values in the left and right hand sides. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>l</varname> + </term> + <listitem> + <para> + The left hand side value. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>r</varname> + </term> + <listitem> + <para> + The right hand side value. + </para> + </listitem> + </varlistentry> + </variablelist> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>lhs</varname> + </term> + <listitem> + <para> + The left hand attribute set of the merge. + </para> + </listitem> + </varlistentry> + <varlistentry> + <term> + <varname>rhs</varname> + </term> + <listitem> + <para> + The right hand attribute set of the merge. + </para> + </listitem> + </varlistentry> + </variablelist> + + <example xml:id="function-library-lib.attrsets.recursiveUpdateUntil-example"> + <title>Recursively merging two attribute sets</title> +<programlisting><![CDATA[ +lib.attrsets.recursiveUpdateUntil (path: l: r: path == ["foo"]) + { + # first attribute set + foo.bar = 1; + foo.baz = 2; + bar = 3; + } + { + #second attribute set + foo.bar = 1; + foo.quz = 2; + baz = 4; + } +=> { + foo.bar = 1; # 'foo.*' from the second set + foo.quz = 2; # + bar = 3; # 'bar' from the first set + baz = 4; # 'baz' from the second set +} + ]]></programlisting> + </example> + </section> </section> |