Re: Closures versus objects

On Sun, 2007-02-18 at 18:22 -0600, Paul F. Dietz wrote:
> Pascal Costanza wrote:
> 
> >
> > On 16 Feb 2007, at 19:22, Gary King wrote:
> >
> >> If Lisp was re-written today, I'd guess that there would be more  use 
> >> of generic functions for things like length. Then we would have:
> >>
> >> (length "butter")  ==> 6
> >> (length #(1 2 3))  ==> 3
> >>
> >> and so on...
> >
> >
> > That's basically what happened in Dylan.
> 
> 
> There's nothing that prevents LENGTH from being implemented as a generic 
> function in a compliant common lisp.  Programs that depend on it being 
> generic will not be portable, however.

Which brings up a good point. Given this observation, why wasn't LENGTH
made a GF when CL was specified? Was CLOS such a late addition and
everybody was afraid of the possible performance impact? Surely, there
was not technical reason that it couldn't have been made generic, as you
say; all old code would have continued working, no?

Over the past couple years, I have really learned to appreciate CLOS and
this is one of those examples where it seems like a good idea wasn't
taken far enough.

-- Dave