RE: [Caml-list] Value shadowing

["David Allsopp" <dra-news@metastack.com>]

> On Wed, Aug 13, 2008 at 09:54:36AM +0100, David Allsopp wrote:
> > Suppose I have this piece of code:
> > 
> > let foo xs =
> >   match xs with
> >     x::xs -> if x
> >              then xs (* Return the tail of the list *)
> >              else xs (* Return the entire list *)
> >   | []    -> raise Exit
>
> I'd find it very counter-intuitive if OCaml behaved like this, and
> annoying if it gave a warning.  Just name the variables to be
> different!

You seem to have missed my point that I wrote the above *in error* so "Just
name the variables to be different!" is a clairvoyant response in this
case... I'm aware that that's what has to change :o)

That said, I do see your point that my proposed warning would mean that you
could never match a list tail with the same name as the whole list - a
definite weakness of my suggestion that I hadn't spotted before.

Personally, I'd be happy to live with always using two names in this context
- but perhaps this should therefore be the job of a home-grown postprocessor
on .annot files, rather than a compiler feature request?


David