"Using Perl 6" multid dispatch example

multi.p6

class Rock     { }
class Paper    { }
class Scissors { }
 
multi wins(Scissors $, Paper    $) { +1 }
multi wins(Paper    $, Rock     $) { +1 }
multi wins(Rock     $, Scissors $) { +1 }
multi wins(::T      $, T        $) {  0 }
multi wins(         $,          $) { -1 }
 
sub play ($a, $b) {
        given wins($a, $b) {
                when +1 { say "Player One wins" }
                when  0 { say "Draw"            }
                when -1 { say "Player two wins" }
 
        }
}
 
play(Rock, Rock); # output: Player two wins
 
given wins(Rock, Rock) {
        when +1 {say "Player One wins"}
        when 0 {say "Draw"}
        when -1 { say "Player two wins"}
} # output: Draw