Re: illegal uses of define in guile

[Marius Vollmer]

Dirk Herrmann <address@hidden> writes:

> Currently, guile allows the following:
>   (if (not (defined? '%load-verbosely))
>       (define %load-verbosely #f))
> as can be found in r4rs.scm.
> 
> This is in contrast to R5RS (maybe even already in contrast to R4RS,
> but I haven't checked that).  Allowing such placements of define will make
> it impossible to determine statically whether after evaluation of the
> form the corresponding identifier will be bound or not.  That is, we
> should disallow this behaviour.

I think we can continue to support it, when people really want us to.
The new.model.txt needs to be adapted a bit, but not much, I think.

This will affect the optimizations a compiler might make, of course,
and maybe we should warn people that such uses of 'define' are
questionable.  We can also disallow them in 'R5RS' mode, when we have
such a thing.

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