bignum support in Emacs with libgmp (was: GNU Emacs-libnettle-libhogweed integration patch v1)

[Ted Zlatanov]

I remember we discussed a while ago that Emacs has bignum support in the
`calc' package and that native Emacs integers were not adequate
sometimes for large arithmetic.

I wanted to propose that we consider exposing the libgmp
(http://gmplib.org/ http://gmplib.org/manual/) functions to the Emacs
core for managing bignums; specifically the mpz, mpq, and mpf functions.
That would give Emacs powerful bignum arithmetic at (I hope) better
speeds than a native ELisp implementation.  libgmp is quite mature.

The existing bignum support can remain as a fallback with refactoring or
just remain as is.  The new functionality would probably have to
introduce new Lisp types.

I don't plan to do the work myself currently but it would make a nice
project if anyone is interested in picking it up.

Ted