Just in case anyone was wondering, in Perl 6:

    sub factorial($n) {
        my $output = 1;
        for 1..$n -> $i {
            $output *= $i;
        }
        $output;
    }

or

    sub factorial2($n) {
        [*] 1..$n;
    }

Pretty anonymous function to add a constant:

    -> $x { $x + 7 }

Really short version:

    * + 7

Named:

    sub plus7($x) {
        $x + 7;
    }