You're looking for one of two things. You can either create a hash with the keys being the second list or you can use grep. 
my @list1 = get_from_some_place();
my @list2 = get_from_some_other_place();

--------

# Hash method

my %lookup_hash;
@lookup_hash{@list2} = undef; # This is a hashslice. We don't care abo
+ut the values.

unless (exists $lookup_hash{$list1[0]})
{
    # Do something here
}

--------

# grep method

unless (grep { $_ eq $list1[0] } @list2)
{
    # Do something here
}

[download]

In general, the hash is faster, but takes more memory.

------
We are the carpenters and bricklayers of the Information Age.

Then there are Damian modules.... *sigh* ... that's not about being less-lazy -- that's about being on some really good drugs -- you know, there is no spoon. - flyingmoose

In reply to Re: ugly nested if's by dragonchild
in thread ugly nested if's by wilbur

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