sub first (&@) {
  my $code = shift;

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

  undef;
}

##</code><code>##

open my $fh, '<', $filename or die "Cannot open '$filename' for reading: $!\n";
tie my @arr, 'Tie::Array::Lazy', [], sub { scalar <$fh> };

first { <whatever> } @arr;