Destructively reverse every cons node in an s-expression

Question

Any ideas how to go about this? I am trying to not create any new nodes.

Answer 1

Call nreverse.

Answer 2

Draw a standard cons-cell diagram of what a list with 5 elements or so looks like. That should give you a big clue right there.

Don't forget to keep a reference to the last cell in the list, which will be your new list head when done.