Re: [Caml-list] Eliminating array bounds check

[Alain Frisch <Alain.Frisch@inria.fr>]

Hello Oleg,

oleg@pobox.com wrote:
> For example:
>  http://pobox.com/~oleg/ftp/ML/eliminating-array-bound-check-literally.ml

>From your code:
=======================================
(* First, we, on off-chance, check if we can obtain type
   eigen-variables via the module system.
*)

module GenT : sig type t val v : t end =
  struct type t = int let v = 1 end
;;
let module M1 = GenT in
let module M2 = GenT in
M1.v = M2.v
;;

(* Alas, the latter succeeds and reports no type error. What did we
   expect: OCaml functors are applicative.
   Fortunately, OCaml supports higher-rank types.
*)
=======================================

What about making GenT a functor and passing it unnamed structures as
arguments? (Ok, you must then trust the client not to apply GenT with
named structures.)

module GenT(X:sig end) : sig type t val v : t end =
  struct type t = int let v = 1 end
;;
let module M1 = GenT(struct end) in
let module M2 = GenT(struct end) in
M1.v = M2.v
;;

You could then simplify the TrustedKernel so as not to use polymorphic
record fields (and also to use a direct style instead of a continuation
style for brand).


-- Alain