max/nix-super
1
0
Fork 0
mirror of https://github.com/privatevoid-net/nix-super.git synced 2024-11-22 14:06:16 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

Merge pull request #2880 from Ma27/document-optional-attrs-with-at-pattern

Browse source 
doc: clarify that optional attrs in a function argument will be ignored unless specified
This commit is contained in:
Eelco Dolstra 2019-05-22 14:14:56 +02:00 committed by GitHub
commit bfc6bdf222
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
1 changed files with 19 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

20
doc/manual/expressions/language-constructs.xml
View file

@ -217,7 +217,25 @@ but can also be written as:
ellipsis(<literal>...</literal>) as you can access attribute names as ellipsis(<literal>...</literal>) as you can access attribute names as
<literal>a</literal>, using <literal>args.a</literal>, which was given as an <literal>a</literal>, using <literal>args.a</literal>, which was given as an
additional attribute to the function. additional attribute to the function.
</para></listitem> </para>
<warning>
<para>
The <literal>args@</literal> expression is bound to the argument passed to the function which
means that attributes with defaults that aren't explicitly specified in the function call
won't cause an evaluation error, but won't exist in <literal>args</literal>.
</para>
<para>
For instance
<programlisting>
let
function = args@{ a ? 23, ... }: args;
in
function {}
</programlisting>
will evaluate to an empty attribute set.
</para>
</warning></listitem>
</itemizedlist> </itemizedlist>