Consider if you can use the none function from List::Util for operations like (! grep ). grep will check the entire list to find all the values that match, but in this case, once you have found a match you might as well stop. Some of the List::Util functions, like first or any or none, will short circuit.

In this example, the variable $j shows how many times the loop body is executed.

use strict;
use warnings;
use List::Util qw(none);

my @list = 1..100;
my $j = 0;

if (! grep { $j++; $_ > 10 } @list ) {
  print 'Didn\'t find any values above 10 ... '
} else {
  print 'Found some values above 10 ... '
}

print "but I had to look at $j values to be sure.\n";

$j = 0;
  
if (none { $j++; $_ > 10 } @list) {
  print 'Didn\'t find any values above 10 ... '
} else {
  print 'Found some values above 10 ... '
}
 
print "but I had to look at $j values to be sure.\n";

[download]

Output:

Found some values above 10 ... but I had to look at 100 values to be s
+ure.
Found some values above 10 ... but I had to look at 11 values to be su
+re.

[download]

Update: forgot to copy the code that actually produces that output!

Dum Spiro Spero

In reply to Re: improve performance by GotToBTru
in thread improve performance by swissknife

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