Merge pull request #42 from Crell/named-args

Describe named arguments.

spec.md

@@ -513,12 +513,12 @@ function fooBarBaz($arg1, &$arg2, $arg3 = [])
 }
 ```
 
-### 4.5 Method and Function Arguments
+### 4.5 Method and Function Parameters
 
 In the argument list, there MUST NOT be a space before each comma, and there
 MUST be one space after each comma.
 
-Method and function arguments with default values MUST go at the end of the argument
+Method and function parameters with default values MUST go at the end of the argument
 list.
 
 ```php
@@ -714,6 +714,13 @@ $app->get('/hello/{name}', function ($name) use ($app) {
 });
 ```
 
+If using named arguments, there MUST NOT be a space between the argument name
+and colon, and there MUST be a single space between the colon and the argument value.
+
+```php
+somefunction($a, b: $b, c: 'c');
+```
+
 Method chaining MAY be put on separate lines, where each subsequent line is indented once. When doing so, the first
 method MUST be on the next line.