Alexander Burger <a...@software-lab.de> writes: Hi Alex,
>> In PicoLisp, the cdr of a circular list always seems to point to the >> beginning of the list. > > Yes, as far as the directy reader/printer syntax is concerned. But you > can easily specify a list where the last cell points to some other > cell. > > For example, in this list of 6 cells the last 3 cells form a circular > list: > > : (1 2 3 . (4 5 6 .)) > -> (1 2 3 . (4 5 6 .)) > : (more @) > 1 > 2 > 3 > 4 > 5 > 6 > 4 > 5 > 6 > 4 > ... > > Personally, I find syntax much simpler and cleaner than using labels. I see, and indeed it looks clean and nice. > What cannot be directly expressed, however, is a pointer into a sublist > of the current list (or even into arbitrary other lists). > > Here you have to resort to "labels", by setting a variable to the > (sub)list in question: > > : (1 2 (3 4 . `(setq "n1" (5 6))) 7 . `"n1") > -> (1 2 (3 4 5 6) 7 5 6) > > : (1 2 3 ~(setq "n2" (4 5 6))) > -> (1 2 3 4 5 6) > : (7 8 ~"n2") > -> (7 8 4 5 6) Does not look as clean and nice as before, but what counts - it can be done, great. Thanks again, I'm glad I asked, it would have taken me forever to (probably not) figure this out. -- cheers, Thorsten -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
