Give set()/bag()/mix() single arg semantics

src/core/set_operators.pm

@@ -312,8 +312,16 @@ only sub infix:<≽>($a, $b --> Bool) {
     $a (>+) $b;
 }
 
-sub set(*@args --> Set) { Set.new(@args) }
-sub bag(*@args --> Bag) { Bag.new(@args) }
-sub mix(*@args --> Mix) { Mix.new(@args) }
+proto sub set(|) { * }
+multi sub set(\value  --> Set) { Set.new(value) }
+multi sub set(**@args --> Set) { Set.new(@args) }
+
+proto sub bag(|) { * }
+multi sub bag(\value  --> Bag) { Bag.new(value) }
+multi sub bag(**@args --> Bag) { Bag.new(@args) }
+
+proto sub mix(|) { * }
+multi sub mix(\value  --> Mix) { Mix.new(value) }
+multi sub mix(**@args --> Mix) { Mix.new(@args) }
 
 # vim: ft=perl6 expandtab sw=4