Roboticus@Roboticus-PC ~
$ perl t.pl
0 is false
0 is false
foo is true
bar is true
fkento is true
true is true
false is true
yes is true
no is true
 is false

Roboticus@Roboticus-PC ~
$ cat t.pl
#!/usr/bin/perl
use strict;
use warnings;

for my $t (0, qw(0 foo bar fkento true false yes no), '') {
  print "$t is ", ($t ? 'true' : 'false'), "\n";
}