unless ( $skipper {item} )  { # not found in list?
[download]

     unless ( $skipper {$item} )  { # not found in list?
[download]

But you might be interested in another approach using hash-slices, which is way faster for big data.

use strict;
use warnings;


my @got      = qw(blue_shirt hat jacket preserver );   # sunscreen);
my @required = qw(preserver sunscreen water_bottle jacket);

# ---------- directly coded

my %required;
@required{@required}=@required;
delete  @required{@got};

warn "Skipper is missing: ", values %required; 


# ---------- or alternative as custom function

warn "Skipper is missing: ", array_minus(@got,@required);  

sub array_minus (\@\@) {
    my ( $got, $required ) = @_;
    my %required;
    @required{@required}=@required;
    delete  @required{@got};
    return values %required; 
}
[download]

Skipper is missing: water_bottle    sunscreen at d:/exp/hash_diff.pl l
+ine 14.
Skipper is missing: sunscreen    water_bottle at d:/exp/hash_diff.pl l
+ine 28.
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sub array_minus (\@\@) {
    my ( $got, $required ) = @_;
    my %required;
    @required{@required}=@required;
    delete  @required{@got};
    return values %required; 
}
[download]

Note also that this function is not correct because the  $got $required array references passed as arguments are never used. As it stands, the code here works only because  @required @got within the function access file-scope lexicals defined earlier in the code. Also, the prototype  array_minus(\@\@) needs to be declared (or the function itself needs to be defined) before the function is invoked for prototyping to be effective.

c:\@Work\Perl\monks>perl
use strict;
use warnings;

sub array_minus (\@\@);

my @got      = qw(blue_shirt hat jacket preserver );
my @required = qw(preserver sunscreen water_bottle jacket);

# ---------- as custom function

warn "Skipper is missing: ", array_minus(@got,@required);

sub array_minus (\@\@) {
    my ( $ar_got, $ar_required ) = @_;
    my %required;
    @required{@$ar_required} = @$ar_required;
    delete  @required{@$ar_got};
    return values %required;
}

__END__
Skipper is missing: water_bottlesunscreen at - line 11.
[download]

---

Give a man a fish:  <%-{-{-{-<

True, my bad!

Thanks for correcting.

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery FootballPerl is like chess, only without the dice}

If you're going for speed, then don't make a needless copy of everything in @required.

my %required;
@required{@required}=();
delete @required{@got};

warn "Skipper is missing: ", keys %required;
[download]

Of course, this assumes string values.

> Of course, this assumes string values.

Not assuming it is why I went this way. It can also handle an array of refs like this.

Though mixed values may clash.

I started a thread here once where I asked for a solution for this, will dig it out tomorrow.

update

couldn't wait Re: Using hashes for set operations... , but doesn't really help.

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery FootballPerl is like chess, only without the dice}

This code reminds me a lot of the exercises in the "Learning Perl Objects, References and Modules" book :)

That book was instrumental of me finally really grasping references in Perl so many years ago.