Perl's grep does not work with dereferenced array

Question

I wanted to find a perl equivalent to a python var in list idiom and stumbled on this.

The perl grep can do a grep { $_ eq $var } @list expression to match the element in list logic.

If I use a derefenced array like grep { $_ eq $var } @$list with $list defined as ['foo', 'bar'], I don't get the same outcome.

Is there a way to make grep work using dereferenced arrays?

Answer 1

That idiom should work fine; I think a code example where it's not working would be helpful. Just as a quickie toy example of this, though:

#!/usr/bin/perl
use strict;
use warnings;

use Test::More;

sub find_var {
    my ($var,$array) = @_;
    print "Testing for $var in [" . join(',',@$array) . "]...\n";
    if ( grep $var eq $_, @$array ) {
        return "found it";
    } else {
        return "no match!\n";
    }
}

my @array = qw(apple pear cherry football);
my $var = 'football';
my $var2 = 'tomato';

is(find_var($var, \@array), 'found it');
is(find_var($var2, \@array), 'found it');
done_testing();

This results in the following output, which indicates that the first test for "football" in the array reference was successful, while the second test for "tomato" was not:

Testing for football in [apple,pear,cherry,football]...
ok 1
Testing for tomato in [apple,pear,cherry,football]...
not ok 2
#   Failed test at array.pl line 22.
#          got: 'no match!
# '
#     expected: 'found it'
1..2
# Looks like you failed 1 test of 2.