Re: Using the GNU GMP Library for Bignums in Emacs

[Paul Eggert]

Tom Tromey wrote:

> 1. Should the C core change the names of things like NUMBERP to FIXNUMP?
>     Similarly should make_number -> make_fixnum?

Yes, we should keep things clear in the C core, and this would definitely be 
clearer. Please do it as a separate commit, though.

> 2. What is (type-of 5)?  Right now 'integer, but arguably perhaps
>     'fixnum is correct.  Gerd's branch did this.

'integer', for the same reason that (type-of 5) doesn't return 'natnum'. fixnum 
and natnum are both subtypes of integer, and the basic type is integer.  The 
other ways of doing this would cause more trouble to user code.

> 3. Should intbig_to_lisp et al be converted to use bignums?
>     I'm inclined to say no, for compatibility.

Yes, that function should now return only fixnums and bignums (assuming GMP is 
available). Of course the reverse functions that converts lisp to C integer also 
needs to work with bignums in C range.

> 4. Should it be possible to make a "low-valued bignum"?

No, as too much Lisp code depends on eq acting like = on fixnums. Although this 
will not work for bignums (unless we take Stefan's suggestion...), it should 
continue to work on integers that can fit into fixnum range.

Thanks for working on this!