>perl -wMstrict -le
"my %hash = qw(one uno  two dos);
 my @y = 5 .. 8;
 ;;
 print 'scalar @y: ', scalar @y;
 print 'does not exist' if not exists $hash{ @y };
 ;;
 $hash{ '4' } = 'four';
 print 'does exist: ', qq{'$hash{ @y }'} if exists $hash{ @y };
"
scalar @y: 4
does not exist
does exist: 'four'