add example of type constraint on an optional argument

Raku · Sep 29, 2016 · 99a8666 · 99a8666
1 parent e5ddbfe
commit 99a8666
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/doc/Type/Signature.pod6 b/doc/Type/Signature.pod6
@@ -150,6 +150,12 @@ the C<where>-clause inside the sub-signature.
     say one-of-them(c=>42);
     # OUTPUT«42␤»
 
+=head3 Constraining Optional Arguments
+
+L<Optional arguments|Optional_and_Mandatory_Parameters> can have constraints, too:
+
+    sub bin2hex($bin, Int $len where {$len >= 0} = 0) { ... }
+
 =head3 Constraining Slurpy Arguments
 
 L<Slurpy arguments|Slurpy_(A.K.A._Variadic)_Parameters> can not have type