One can create a key as integer 0 and access it with key boolean false but one cannot create an array with boolean false as the key.  In otherwords:

$arr = array(false => 'bar');      // array()
$arr = array((int)false => 'bar'); // array(0=>'bar')

$arr = array(0 => 'bar');
print $arr[false];            // bar
print $arr[(int)false];       // bar

This seems inconsistent.  From the documentation:

Using TRUE as a key will evalute to integer 1 as key. Using FALSE as a key will evalute to integer  0 as key.

Please explain the reasoning behind the current behavior.