Idiomatically you would do this:

my @list = qw( foo bar baz );
my %hash;
$hash{$_}++ for @list;

# now do a lookup
if ( $hash{$look_this_up} ) {
    # blah
}

use Data::Dumper;
print Dumper \%hash

__DATA__
$VAR1 = {
          'foo' => '1',
          'baz' => '1',
          'bar' => '1'
        };
[download]

This populates the hash with identical values (ie 1). It means that $hash{$value} will be true if $value is in the hash or false if it is not. We are really only interested in the keys for the fast lookup but having a true value lets us avoid having to use exists

cheers

tachyon

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