gistfile1.pl

#!perl
use strict;
use warnings;
use Test::More;

sub r_explicit { return 0; }
sub r_bare     { return;   }

# Probably not what you expected
my %hash = (
  first  => r_bare,
	second => r_explicit,
);

ok(  exists $hash{'first'},  "'first' exists" );
ok(! exists $hash{'second'}, "'second' unset" );

# Not list context, as it happens
ok(! r_explicit, "r_explicit is false" ); # Passes

# Works like you'd hope
if ( r_explicit ) {
	fail("r_explicit is false");
} else {
	pass("r_explicit is false");
}

# Jumping through some real hoops here...
my $wrong_answer =()= r_explicit;
ok( $wrong_answer, "I blame the =()= operator" );

my @wrong_answer = r_explicit;
if ( @wrong_answer ) {
	pass("Who evaluates a list for truth, anyway?");
} else {
	fail("Who evaluates a list for truth, anyway?");
}