Re: [Chicken-users] redefinitions

[Felix Winkelmann]

On Fri, 23 Jul 2004 08:19:30 +0200, Michele Simionato  
<address@hidden> wrote:

> Chicken made a lot of progress in these four years and I am
> sure more will follow in the near feature :)

Hopefully, it will - if people keep helping, of course!

> One option is to make globals available only in the module
> where they are defined, i.e. not exported unless explicitely
> declared. But this means a module system and use some
> import mechanism different from "load", so let me not
> pursue that.

Right, One could use the psyntax module system, or, if you
use compiled code, the `export' declaration.

> A (apparently) simpler solution would be to warn the user
> if a name is redefined. I mean
>
> (define TAB-WIDTH 4)
> (define TAB-WIDTH 8) ; error
>
> should raise a redefinition error (that would be my preferred
> behavior) or at least print a redefinition warning (if raising
> the error would be too radical). The right way to
> redefine things should be via set! :
>
> (define TAB-WIDTH 4)
> (set! TAB-WIDTH 8) ; ok
>
> [...]
>
> So I want to know if there is some hope to get this
> "fixed", at least having a warning when things are
> redefined in the same lexical scoping using define
> instead of set! (of course shadowing a name with internal
> defines or let is fine and should not raise any warning).
>
> What do you think?

I think this is a reasonable thing to do. Currently `define'
is just a macro that expands into `set!', so it might need
some internal machinery to handle this properly. You are
talking about both interpreted and compiled code, right?


cheers,
felix