Re: [Caml-list] Feature request.

[Alain.Frisch@ens.fr]

On Wed, 9 Apr 2003, Jean-Christophe Filliatre wrote:

> In SML, there used to be  local exceptions (exception E in ...) and it
> was breaking type soundness, since an exception could obviously escape
> the scope  of its declaration

What kind of type unsoundness ?  A local exception cannot be matched
outside its scope (except by match-all pattern, of course), and that's
all.

> I guess  that with a  "type ... in"  construct, a type  could probably
> escape its scope the same  way, leading to serious issues in assigning
> legal types to expressions.

This is exactly the same issue as for local modules, and OCaml can detect
it.

# let module A = struct type t = X end in A.X;;
This `let module' expression has type A.t
In this type, the locally bound module name A escapes its scope

-- Alain

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