Associative Operators? (Was: Re: [NOVICE] Out of frying pan, into fire)

Seth McQuale pointed out that the follwing does not work: SELECT LASTNAME || ',' || FIRSTNAME [AS] NAME FROM FRIENDS;

The solution, was: SELECT ( LASTNAME || ',' ) || FIRSTNAME AS NAME FROM FRIENDS;

I looked at pg_operator and didn't see any flag to mark
an operator as 'associative'.   Perhaps if we added a flag
like this, the re-write system could be modified to handle
cases like this.

Thoughts?

Clark Evans