Sujet : Re: Church numerals in early lisp implementations?
De : jshem (at) *nospam* yaxenu.org (Julieta Shem)
Groupes : comp.lang.lispDate : 12. May 2024, 21:55:46
Autres entêtes
Organisation : A noiseless patient Spider
Message-ID : <877cfykdod.fsf@yaxenu.org>
References : 1 2
Alan Bawden <
alan@csail.mit.edu> writes:
Julieta Shem <jshem@yaxenu.org> writes:
>
McCarthy wrote this in ``History of Lisp''.
>
> Numbers were originally implemented in LISP I as lists of atoms, and
> this proved too slow for all but the simplest computations.
>
Was that Church numerals?
>
Certainly not.
>
The "atoms" is question were probably machine words containing the
digits of the number in some suitable base. I would guess base 2^36 or
2^35, depending on how they chose to represent negative numbers --
similar to the way GMP still works today. But I don't know for sure.
I've never seen this documented anywhere.
Do you know if they have big numbers in those early implementations?
(Why would they use a list of things?) I'm now thinking that by ``list
of atoms'' (and with the light of from your post) they were supporting
big numbers. Their algorithms were perhaps naive, explaining ``the too
slow for all but the simplest computations''. Thanks!