Re: (set! (@@ MOD NAME) EXP) considered harmful

[Mark H Weaver]

Sorry, I meant to say that (set! (@ MOD NAME) EXP) should be
considered harmful as well.

     Mark


On Wed, Sep 02, 2009 at 12:17:11PM -0400, Mark H Weaver wrote:
> The ability to set! arbitrary module top-level variables from outside
> the module, using the syntax (set! (@@ MOD NAME) EXP), destroys our
> ability to several important optimizations.
> 
> As long as such ability exists, we must pessimistically assume that
> any module top-level variable might change at any time, which means,
> for example, that we cannot inline top-level procedure applications
> from within the module itself.  This could be a HUGE efficiency win in
> the common case where such top-level procedures are never set! from
> within the module.
> 
> Now that we have proper hygienic macros, is this functionality still
> required?  If we're going to remove it, pre-2.0 seems like a good time
> to do so.  We won't get another opportunity for several years.
> 
>      Mark
>