When do variables output properly in skeletons functions?

Question

I'm trying to write a skeleton-function to output expressions in a loop. Out of a loop I can do,

(define-skeleton test
    ""
    > "a")

When I evaluate this function it outputs "a" into the working buffer as desired. However, I'm having issues when inserting this into a loop. I now have,

(define-skeleton test
  "A test skeleton"
  (let ((i 1))
  (while (< i 5)
   >"a"
   (setq i (1+ i)))))

I would expect this to output "aaaaa". However, instead nothing is outputted into the working buffer in this case. What is happening when I insert the loop?

Answer 1

The > somestring skeleton dsl does not work inside lisp forms. You can however concatenate the string inside a loop:

(define-skeleton barbaz
    ""
  ""
  (let ((s ""))
    (dotimes (i 5)
      (setq s (concat s "a")))
    s)
  )

My understanding is that code such as > "a"

only works at the first nesting level inside a skeleton.

[EDIT] Regarding your question

What is happening when I insert the loop?

The return value of the let form (that is, the return value of the while form)is inserted. I do not know why it does not raise an error when evaluating > "a", but the return value of a while form is nil, so nothing is inserted.