use strict; use warnings;
use List::MoreUtils qw[firstidx];

sub cull (&\@) {
    my ($code, $array) = (shift, shift);
    my @matches;
    my $count;
    
    # let List::MoreUtils (fast!) find the items
    # splice() returns the items removed....
    while ( (my $idx = firstidx { $code->() } @$array) > -1 ) { 
        my $item = splice(@$array,$idx,1);
        wantarray ? push(@matches, $item) : $count++;
    }
    
    wantarray ? @matches : $count;
}

my @test = qw[how I wish I could remember pi easily];
my @new = cull { $_ eq 'I' } @test;

print join(':',@new), "\n";
print join(':',@test), "\n";