Say I have for example
(define sample '("a" "b" "c"))
How would I go about creating a nested loop that will work with sample.
(define (runthis a)
(cond
(char? (car a)) ;given that this condition is true I go on to the nested loop
(define (work sample)
<dosomething>
(work (cdr sample))))
(else (write " ")
(runthis(cdr a))))
is this the correct template for a basic nested loop?
If you need nested loops, I recommend using for instead. Here is a small, silly example. The outer loops runs through the words in the list one at a time. If the current word begins with an r, then the inner loop will print each character one at a time.
#lang racket
(define (print-words-beginning-with-r words)
(for ([word words]
#:when (char=? (string-ref word 0) #\r))
(for ([c word])
(display c))
(newline)))
(print-words-beginning-with-r '("racket" "rocks" "!"))
This outputs
racket
rocks
I don't have a Scheme interpreter handy, but that doesn't look like it'll run.
I'm not sure what exactly you mean by "nested loop," or what requirement you're attempting to satisfy, but lots of nesting and long functions are discouraged in Scheme because they impact readability/clarity. Are you trying to replicate this sort of behavior?
while(foo) {
while(bar) {
// Frob the fizzbits
}
}
I would recommend something like this, which is functionally equivalent but easier to grok:
(define (inner-loop the-list)
; do things
)
(define (outer-loop the-list)
(cond (char? (car a)) (inner-loop the-list)
(else (write " "))))
Another possibility would be the named let, as in:
(define (runthis a)
(cond
((char? (car a))
(let loop ((sample a))
(cond
((null? sample) '())
(else (display (car sample))
(loop (cdr sample))))))
(else (write " "))))
