Re: int4 <-> bool casts

Neil Conway wrote:
> > I believe I would have objected to an int/bool cast. I do so now
> > anyway.
>
> On what grounds?

I can think of a couple of reasons:

- Casting back and forth does not preserve information.  (This may be
true for some other type pairs as well, but in this case it's true in
almost every instance.)

- It's an arbitary definition that is not obviously supported by
mathematical or similar principles.

- It opens the door for other silly casts like empty string => false,
non-empty string => true.

- It's unnecessary because you can express the same thing using other
expressions that clearly state what they do.

--
Peter Eisentraut
http://developer.postgresql.org/~petere/