Re: Using the GNU GMP Library for Bignums in Emacs

[Paul Eggert <eggert@cs.ucla.edu>]

On 07/10/2018 09:48 AM, Helmut Eller wrote:
>> If so, why would someone want to specialize a method just for fixnums,
>> as opposed to a method for integers?
> Some important functions only for fixnums but not for bignums.
> E.g. goto-char or aref.

Both of these functions have limits that are not relevant to fixnums; 
they have limits based on something else. For example, goto-char is 
limited to point-min..point-max, and aref is limited to 0..length-1. We 
will want both functions to work on bignums, since we will want to allow 
buffer sizes and bool vector lengths that do not fit into fixnums.

And even if these functions' limits were relevant to fixnums, I don't 
see why one would want to specialize a method just for fixnums as 
opposed to settling for specializing it to integers. The method would 
accept an integer, and then if it used a fixnum-only goto-char or aref 
that would signal an error, just as it would for any other out-of-range 
integer. There would be no need to specialize the method to fixnums.

So I'm still not seeing the actual use cases that would suggest that 
(type-of 5) should not continue to return 'integer'.