Re: Issue FIXNUM-NON-PORTABLE, v4

[Jeff Dalton <jeff%aiai.edinburgh.ac.uk@NSS.Cs.Ucl.AC.UK>]

>                  Also, in most implementations fixnums are big enough to
>     contain the address part of a pointer to a data object.  Therefore,
>     they are always big enough to count objects.
>     
> Note that this proposal does not guarantee that fixnums will be large
> enough for your purposes; all Common Lisp systems will need more than
> 16 address bits...

That's one of the problems with saying 16 bits: it might increase the
likelihood that implementations will do something that losing.  It would
be nice if there were some way to test whether fixmuns were big enough
(if we can't actually guarantee it), but it's worth noting that right
now fixnums work better for this purpose that any particular number of
bits I might pick.