Perl 6 introduces the concept of so-called pointy blocks (or pointy arrow blocks). These are anonymous closure blocks, which return a reference to the function and can take arguments.
The syntax of defining pointy blocks is an arrow -> followed by the argument list and a block of code.
my $cube = -> $x {$x ** 3};
say $cube(3); # 27
Here, the block {$x ** 3}, which takes one argument $x, is created first. Then, it is called using a variable $cube as a reference to the function: $cube(3).
Pointy blocks are quite handy in loops.
for 1..10 -> $c {
say $c;
}
The for loop takes two arguments: the range 1..10 and the block of code with the argument $c. The whole construction looks like syntactic sugar for loops.
There can be more than one argument. In that case, list them all after an arrow.
my $pow = -> $x, $p {$x ** $p};
say $pow(2, 15); # 32768
The same works with loops and with other Perl elements where you need passing anonymous code blocks.
for 0..9 -> $i, $j {
say $i + $j;
}
In a loop iteration, two values from the list are consumed each time. So, the loop iterates five times and prints the sum of the pairs of numbers: 1, 5, 9, 13 and 17.
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