Hi I'm looking into wrapping the Nat module from the Num package. I
can't find any documentation for it, but the source + a bit of guesswork makes
it somewhat accessible.
However, superficially at least it looks like this library enables
arbitrary getting/setting of bytes in the program's heap, with no
bounds checking. Please tell me it's not so!
$ ocaml dynlink.cma
Objective Caml version 3.12.0+beta1
# #require num;;
# open Nat;;
# let nx = nat_of_int 3;;
# let dump () = List.map (fun x - nth_digit_nat nx x) [0;1;2;3;4;5;6;7;8];;
# dump ();;
- : int list =
[3; 1024; 1; 3074; 139752628822496; 1; 139752628800520; 1024; 1]
# set_digit_nat nx 6 111999111; nth_digit_nat nx 6;;
- : int = 111999111
# dump();;
- : int list = [3; 1024; 1; 3074; 139752628822496; 1; 111999111; 1024; 1]
I found this old message in the mailing list, but it seems to have gotten no
answer:
On Fri, Nov 07, 2008 at 10:33:41AM +0100, Andrej Bauer wrote:
The Nat module in the Num library is not documented in the official
documentation, but is documented in the 1992 tech report by Valérie
Ménissier-Morain. I would ilke to use Ocaml-only library for big
integers which has bit shifting operations. Big_int does not, but Nat
does. Is Nat stable and safe to use by people who are neither
French, nor at INRIA, nor are they Ocaml developers?
Before someone tells me I should use GMP and/or MPFR: I am already
using them, I am just rewriting a piece of code so that it can be
optionally compiled with pure ocaml.
--
Jim Pryor
prof...@jimpryor.net
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