Almost there. first itself is (almost) perfectly respectful of a lazy @_. In List::Util, the pure-perl version of first() is: 
sub first (&@) {
  my $code = shift;

  foreach (@_) {
    return $_ if &{$code}();
  }

  undef;
}

[download]
The issue is (almost) completely that @_ is not lazy in the slightest. This is one of the biggest changes no-one will notice in Perl6 - the addition of the concept of truly lazy lists. You could code up something lazier with Tie::Array::Lazy. Maybe something like: 
open my $fh, '<', $filename or die "Cannot open '$filename' for readin
+g: $!\n";
tie my @arr, 'Tie::Array::Lazy', [], sub { scalar <$fh> };

first { <whatever> } @arr;

[download]
(Note that this is completely untested - I've never used Tie::Array::Lazy in my life.)
My criteria for good software:
  1. Does it work?
  2. Can someone else come in, make a change, and be reasonably certain no bugs were introduced?

In reply to Re^3: Grepping with Perl: How to stop after first match? by dragonchild
in thread Grepping with Perl: How to stop after first match? by paulnovl

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