I am not entirely sure this answer is what you are looking for, but the
following generator
will produce the pairs of the list instead of the elements.
(define (in-pairs xs)
(make-do-sequence
(λ ()
(define (pos->element p) p)
(define (next-position p) (cdr p))
(define initial-position xs)
(define (continue-with-pos? p) (pair? p))
(values pos->element
next-position
initial-position
continue-with-pos?
#f #f))))
Example:
>* (for ([p (in-pairs '(1 2 3 4))])
* (displayln p))
(1 2 3 4)
(2 3 4)
(3 4)
(4)
So you can use
(define descriptions (list "this" "that"))
(define amounts (list 4467.61 2428.37))
(for ([d descriptions] [ds (in-pairs descriptions)])
[a amounts] [as (in-pairs amounts])
...)
And use ds and as to get to other descriptions/amounts than the current
(which are in d and a).
/Jens Axel
Den fre. 14. jun. 2019 kl. 16.45 skrev Sanjeev Sharma <throw...@gmail.com>:
> within this for loop is there any way to access different pieces of the
> description and amt? car-ing and cdr-ing for example?
>
> Or move the identifier definitions into the let*, and pass those to for in
> some way?
>
> (let*((ratio 9/12))
> (for((description(list "this" "that"))
> (amt(list 4467.61 2428.37)))
> (printf"~a ~a: changed values\n"
> description
> (cat(* amt ratio) -2.))))
>
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