how to get depth of list

A simple recursive function will do this:

procedure(abListDepth(lst @optional (depth 0) "lx" )
  let(((newDepth depth))
    foreach(elem lst
      when(listp(elem)
        newDepth=max(newDepth abListDepth(elem add1(depth)))
      )
    )
    newDepth
  )
)

Regards,

Andrew.

Hi Andrew,

Thanks a lot. As always, It works perfectly. :-D

Best regards,

law

 I had it also, but without foreach loop. I suppose add1 is faster than var+1 ?

A='(((1 2 3) 4 5) 6 7 8)

(defun carDepth (lst @optional (i 0))
(cond
((null lst) i)   ;=> nothing in the list anymore = stop condition
((atom (car lst)) printf("Parse i:%d : %L\n" i lst) (carDepth (cdr lst) i))  ; when first element is single process it (nothing) and go further is returned
(t                 (max (carDepth (car lst) i+1 ) (carDepth (cdr lst) i))) ; else append head and tail with the function itself recursing
))

carDepth(A) ;=> 2

 You may remove the printf statment

The difference between +1 and add1() is miniscule (in fact from a quick profile I just did with 100 million adds, it made a difference of less than 2 seconds, and in fact add1() was slower - but I didn't check to ensure it was statistically significant, but it wouldn't be worth worrying about for efficiency because the difference is so tiny.

However, the approach you have taken (which is a very "SCHEME" way of doing things), whilst simple, does suffer from the fact that the extreme use of recursion will mean you are much more likely to hit SKILL's stack limit:

I ran with a list with 10000 elements in it, and I get:

*Error* unknown: Runtime Stack Overflow!!!

In my approach, I was only using recursion for the actually nested hierarchy of the list, not the length of the list. Mapping (i.e. foreach) doesn't have this problem.

Andrew.

It is always nice to have your wise point of you!

Thanks