Postgresql doesn't understand the unary plus

I definitly consider this a bug but other people may disagree with me. What
I want to know is if it's excluded for any particular reason.

=> select -1;
?column?
--------
      -1
=> select +1;
ERROR:  Unable to identify a left operator '+' for type 'int4'
        You may need to add parentheses or an explicit cast

--
Martijn van Oosterhout