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-rw-r--r--doc/manual/writing-nix-expressions.xml18
1 files changed, 18 insertions, 0 deletions
diff --git a/doc/manual/writing-nix-expressions.xml b/doc/manual/writing-nix-expressions.xml
index 1cc5bb95b..9770e9182 100644
--- a/doc/manual/writing-nix-expressions.xml
+++ b/doc/manual/writing-nix-expressions.xml
@@ -1362,6 +1362,24 @@ is also available as <function>builtins.derivation</function>.</para>
</varlistentry>
+ <varlistentry><term><function>builtins.attrNames</function>
+ <replaceable>attrs</replaceable></term>
+
+ <listitem><para>Return the names of the attributes in the
+ attribute set <replaceable>attrs</replaceable> in a sorted list.
+ For instance, <literal>builtins.attrNames {y = 1; x =
+ "foo";}</literal> evaluates to <literal>["x" "y"]</literal>.
+ There is no built-in function <function>attrValues</function>, but
+ you can easily define it yourself:
+
+<programlisting>
+attrValues = attrs: map (name: builtins.getAttr name attrs) (builtins.attrNames attrs);</programlisting>
+
+ </para></listitem>
+
+ </varlistentry>
+
+
<varlistentry><term><function>baseNameOf</function> <replaceable>s</replaceable></term>
<listitem><para>Return the <emphasis>base name</emphasis> of the