On Tue, Feb 11, 2025 at 11:38 PM Alexander Burger <picolisp@software-lab.de> wrote:
> I would say it is a cell with a non-NIL and non-atomic CDR, then (1 . 2) > is not a list but > > (1 . NIL) # (1) > > or > > (1 . (2 . NIL)) # (1 2) > > is. > > 👍 BTW, 'fin' can be used to distinguish them: > > : (fin (1 2)) > -> NIL > : (fin (1 2 . 3)) > -> 3 > > 'fin' may be the function I am looking for. I will have to play with it a bit and probably rethink my data structure. I was trying to 'rotate' a tree structure and for the purpose of 'set' I needed to distinguish between (1 . 2) (1 2) (1 . (2 3 4)) (1 (2 3 4)) In the case of the pair, I can't use 'set' to update the cdr and would have to use 'con' and reference the appropriate node. : (lst? (cdr Pair)) > I tried that expression, but the way I was thinking about lists, and trying to use them, didn't give me the results I expected. : (lst? (cdr (1 . 2))) -> NIL : (lst? (cdr (1 2))) -> T : (lst? (cdr (1 . (2 3 4)))) -> T : (lst? (cdr (1 (2 3 4)))) -> T /Lindsay
