26.creating-operators.adoc

通过使用 sub 关键字后跟 prefix, infix, postfix, circumfix, 或 postcircumfix; 声明运算符; 然后是冒号结构中的冒号和运算符名称。对于（后）环缀操作符，用空格分隔这两部分。

sub hello {
    say "Hello, world!";
}

say &hello.^name;   # OUTPUT: «Sub␤»
hello;              # OUTPUT: «Hello, world!␤»

my $s = sub ($a, $b) { $a + $b };
say $s.^name;       # OUTPUT: «Sub␤»
say $s(2, 5);       # OUTPUT: «7␤»

# Alternatively we could create a more
# general operator to sum n numbers
sub prefix:<Σ>( *@number-list ) {
    [+] @number-list
}

say Σ (13, 16, 1); # OUTPUT: «30␤»

sub infix:<:=:>( $a is rw, $b is rw ) {
    ($a, $b) = ($b, $a)
}

my ($num, $letter) = ('A', 3);
say $num;          # OUTPUT: «A␤»
say $letter;       # OUTPUT: «3␤»

# Swap two variables' values
$num :=: $letter;

say $num;          # OUTPUT: «3␤»
say $letter;       # OUTPUT: «A␤»

sub postfix:<!>( Int $num where * >= 0 ) { [*] 1..$num }
say 0!;            # OUTPUT: «1␤»
say 5!;            # OUTPUT: «120␤»

sub postfix:<♥>( $a ) { say „I love $a!“ }
42♥;               # OUTPUT: «I love 42!␤»

sub postcircumfix:<⸨ ⸩>( Positional $a, Whatever ) {
    say $a[0], '…', $a[*-1]
}

[1,2,3,4]⸨*⸩;      # OUTPUT: «1…4␤»

constant term:<♥> = "♥"; # We don't want to quote "love", do we?
sub circumfix:<α ω>( $a ) {
    say „$a is the beginning and the end.“
};

α♥ω;               # OUTPUT: «♥ is the beginning and the end.␤»