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Re: Changing the environment

Jost Boekemeier <jostobfe@linux.zrz.TU-Berlin.DE> writes:

> > In Scheme, you can't change the environment of a closure, so "x" and
>
> (define cl (let ((x 1) (y 2)) (lambda () (display HUGO))))
> (procedure-environment cl) -> (((y x) 2 1) #<procedure (symbol define?)>)
> 
> Is it save so change (extend) that list?

No.  It will conflict with the memoization that the Guile evaluator
performs.

Look at this example:

    (define HUGO 18)
    (define cl (let ((x 1) (y 2)) (lambda () (display HUGO))))
    (cl) -> 18
    (set-car! (procedure-environment cl) '((y x HUGO) 2 1 9))
    (cl) -> 18

Once cl has been executed it has memoized where the bindings are for
its variables.  The use of HUGO has been connected to the global
define, once and for all.