my $foo = getFoo() || '';
  if ($foo =~ /bar/ ){ ... }

##</code><code>##

  my $foo = getFoo() ? 1 : 0;
  if ( $foo ){ ... }

##</code><code>##

$a // $b;   # short for:  defined($a) ?? $a :: $b
$pi //= 3;
# so could do (of course perl6 only):
if( $foo // '' eq "true" ){ ... }
# or
my $foo = getFoo();
$foo //= '';
if( $foo eq "true" ){ ... }