I solved the same exercise some weeks ago, without using `.cursor` pragma
though.
After adding the pragma, my code kept working flawlessly. Even after changing
the approach to use a similar `insert` proc as provided in the question.
After some tinkering around I noticed that I used the object constructor to its
full power and already set `prev` and `next` fields here, which even allows to
shorten the `insert` proc a little bit
proc insert[T](list: var LinkedList[T]; prev, next: ListNode[T]; val: T) =
let node = ListNode[T](val: val, prev: prev, next: next)
if prev.isNil:
list.first = node
else:
#node.prev = prev # (redundant)
prev.next = node
if next.isNil:
list.last = node
else:
#node.next = next # (redundant)
next.prev = node
Run
This now seems to work perfectly fine with the rest of the given code snippet.
However I'm not able to explain why the initial solution didn't work. Maybe
someone else can, based on my observations.
