>perl -wMstrict -MData::Dump -le
"use List::Util      qw(first);
 use List::MoreUtils qw(any);
 ;;
 my @a = (1, 2, 3, 4, 5);
 my @b = (9, 8, 2, 1, 5);
 my @z;
 ;;
 $_ = 'foo';
 { local $_;
   for my $elem ( @a ){
     push @z, $_ = ( first { $elem eq $_ } @b ) ? '+' : '-';
     }
   }
 print @z;
 print qq{\$_ == '$_'};
 ;;;;
 @z = ();
 for my $elem (@a) {
   push @z, (any { $_ == $elem } @b) ? '+' : '-';
   }
 print @z;
 ;;;;
 @z = map { my $ae = $_;  (any { $ae == $_ } @b) ? '+' : '-' } @a;
 print @z;
"
++--+
$_ == 'foo'
++--+
++--+