[Types-sig] const (was: PyDL RFC 0.02)

[Paul Prescod]

Greg Stein wrote:
> 
> p.s. I'd recommend assignment enforcement over the notion of const; the
>      former seems to be more easily enforcable at runtime.

I think we need both. We need to be able to enforce the TYPES of
assignments and we need to sometimes say that an object is not
modifiable, for all of the things we currently use tuples, files open
for read and other read-only objects for.

 Paul Prescod