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nixpkgs docs: document mapAttrsRecursiveCond

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Graham Christensen 2018-10-12 15:22:41 -04:00
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doc/functions/library/attrsets.xml
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@ -1049,4 +1049,127 @@ mapAttrsRecursive
]]></programlisting>
</example>
</section>
<section xml:id="function-library-lib.attrsets.mapAttrsRecursiveCond">
<title><function>lib.attrsets.mapAttrsRecursiveCond</function></title>
<subtitle><literal>mapAttrsRecursiveCond :: (AttrSet -> Bool) -> ([ String ] -> Any -> Any) -> AttrSet -> AttrSet</literal>
</subtitle>
<xi:include href="./locations.xml" xpointer="lib.attrsets.mapAttrsRecursiveCond" />
<para>
Like <function>mapAttrsRecursive</function>, but it takes an additional
predicate function that tells it whether to recursive into an attribute set.
If it returns false, <function>mapAttrsRecursiveCond</function> does not
recurse, but does apply the map function. It is returns true, it does
recurse, and does not apply the map function.
</para>
<variablelist>
<varlistentry>
<term>
<varname>cond</varname>
</term>
<listitem>
<para>
<literal>(AttrSet -> Bool)</literal>
</para>
<para>
Determine if <function>mapAttrsRecursive</function> should recurse deeper
in to the attribute set.
</para>
<variablelist>
<varlistentry>
<term>
<varname>attributeset</varname>
</term>
<listitem>
<para>
An attribute set.
</para>
</listitem>
</varlistentry>
</variablelist>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>f</varname>
</term>
<listitem>
<para>
<literal>[ String ] -> Any -> Any</literal>
</para>
<para>
Given a list of attribute names and value, return a new value.
</para>
<variablelist>
<varlistentry>
<term>
<varname>name_path</varname>
</term>
<listitem>
<para>
The list of attribute names to this value.
</para>
<para>
For example, the <varname>name_path</varname> for the
<literal>example</literal> string in the attribute set <literal>{ foo
= { bar = "example"; }; }</literal> is <literal>[ "foo" "bar"
]</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>value</varname>
</term>
<listitem>
<para>
The attribute's value.
</para>
</listitem>
</varlistentry>
</variablelist>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>set</varname>
</term>
<listitem>
<para>
The attribute set to recursively map over.
</para>
</listitem>
</varlistentry>
</variablelist>
<example xml:id="function-library-lib.attrsets.mapAttrsRecursiveCond-example">
<title>Only convert attribute values to JSON if the containing attribute set is marked for recursion</title>
<programlisting><![CDATA[
lib.attrsets.mapAttrsRecursiveCond
({ recurse ? false, ... }: recurse)
(name: value: builtins.toJSON value)
{
dorecur = {
recurse = true;
hello = "there";
};
dontrecur = {
converted-to- = "json";
};
}
=> {
dorecur = {
hello = "\"there\"";
recurse = "true";
};
dontrecur = "{\"converted-to\":\"json\"}";
}
]]></programlisting>
</example>
</section>
</section>