Re: illegal uses of define in guile

[Bruce Korb]

Dirk Herrmann wrote:

> >   (if (some-sort-of-context-test)
> >       (begin
> >         (define mumble ....)
> >         ...
> >   )   )
> >
> > 'cuz that's where I'd really have my problem.  :-(
> 
> I wonder what people's objective is when they use these constructs?

My guess is that you are thinking about a program written entirely
in Scheme.  In my context, I have a list of things that need doing,
among them defining a scheme value that may even be derived from
non-scheme information.  Later on, I'll test ``(some-sort-of-context-test)''
or, even, whether or not "mumble" got defined in order to decide
about what to do.  This "later on" occurrs in a completely different
part of my program.  Remember, this all gets embedded in the context
of an encompassing program.

> Do
> you really want to construct two different top-level environments, where
> once the symbol has a definition and once it has not?  Are you (mis)using
> the definedness of a symbol as a means to communicate boolean values?

Sometimes.  Not usually, though, but given that the function
(defined? ...) exists, I've used it to decide program flow.