Re: [Chicken-users] dynamic scoping

[Patrick Useldinger]

On 26/06/2013 23:47, Daniel Ajoy wrote:
> "add" binds a to 1 at the moment of definition.
>
> #;48> (define a 1)
> #;49> (define (add x) (+ x a) )
> #;50> (add 10)
> 11
> #;51> (let ((a 100) ) (add 10) )
> 11
>
> Is there a way to give a different value of "a" to add, so that,
> something like this happens:
>
> (let ((a 100) ) (add 10) )
> 110

(define a (make-parameter 1))
(define (add x) (+ x (a)))
(add 10)
(parameterize ((a 100))
  (add 10))
(add 10)

yields
11
110
11