Run subroutine n number of times - perl

Question

I have this perl code below:
use strict;
use warnings;
sub powerset(&#) {
my $callback = shift;
my $bitmask = '';
my $bytes = #_/8;
{
my #indices = grep vec($bitmask, $_, 1), 0..$#_;
$callback->( #_[#indices] );
++vec($bitmask, $_, 8) and last for 0 .. $bytes;
redo if #indices != #_;
}
}
powerset { print "[#_]\n" } 1..21;
I'm trying to figure out how I can only run n times (say 6 times the powerset subroutine). i tried use it:
$x = 0;
while ($x <= 6) {
$x ++;
powerset() ;
}
On run 6 times I mean run to the sixth printed line, in this case to powerset {print "[#_]\n"} 1..21; matches up to the impression of
[]
[1]
[2]
[1 2]
[3]
[1 3]
[2 3]
But I don't know where I would apply it $x = 0; while ($x <= 6) { $x ++; powerset() ; }, if inside the sub powerset() or outside, it seems to me that inside the sub because where the routine is happening.
i know i should use die or return to get out of running a subroutine and that somewhere in while i should use maybe else, but i still don't see how to structure this in the code.
I feel that I should better understand the function of the variables $bitmask, $bytes, $callback, because as it is a lazy evaluation, the way of counting the execution is different.
Further research on how to run a perl subroutine leads me to questions about using timers that depend on the elapsed time in seconds rather than the number of times the subroutine is executed.

Answer 1

Here is an example of how you can constrain the number of times the callback is called:
use feature qw(state);
use strict;
use warnings;
sub powerset(&#) {
my $callback = shift;
my $bitmask = '';
my $bytes = #_/8;
{
my #indices = grep vec($bitmask, $_, 1), 0..$#_;
$callback->( #_[#indices] );
++vec($bitmask, $_, 8) and last for 0 .. $bytes;
redo if #indices != #_;
}
}
my $limit = 6;
powerset
{
state $counter = 0;
die "limit reached" if ++$counter > $limit;
print "[#_]\n"
}
1..21;