Hey Nick,

The difference really only matters if what you're checking has a false value (that you may not know about, such as when looping through a hash). A false value is still defined:

perl -wMstrict -E 'my $x=0; say $x||1; say $x//2;'
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Update: here's a tiny example that shows that in a larger application, not checking for defined can be an issue when you aren't explicitly looking for truth:

use warnings;
use strict;

this(arg => 0);

sub this {
    my %args = @_;
    do_something("if\n") if $args{arg};
    do_something("if def\n") if defined $args{arg};
}
sub do_something{
    print shift;
}
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