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.

score 3 · Answer 1 · answered Sep 29 '09 at 17:14

3

answered Sep 29 '09 at 17:14

Pete Kirkham

If it's not homework, that's the right answer (just make sure to assign the result to something, like (setf foo-prime (nreverse foo))). If it's homework, I'd rather the questioner said so. – David Thornley Oct 02 '09 at 21:56

score 1 · Answer 2 · answered Oct 02 '09 at 21:37

1

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.

answered Oct 02 '09 at 21:37

Michael H.

2 Answers2