Hi Lindsay, > # append > : (bench (let (N ()) (for X 10000 (setq N (append N '(NIL)))) (length N))) > 0.548 sec > -> 10000 > > # cons > : (bench (let (N '()) (for X 10000 (setq N (cons NIL N))) (length N))) > 0.000 sec > -> 10000
'append' in such a loop is a lot slower than a straightforward 'cons', because 'cons' creates only a single new cell and puts it in front of the existing list, while 'append' makes a copy of the whole list (as it is non-destructive) and then 'conc's the new cell. > # conc > : (bench (let (N (list)) (for X 9999 (conc N (list))) (length N))) > 0.067 sec > -> 10000 > ... > Interestingly, I was expecting conc to be faster then (setq..(cons..). At > least in this case, it was not. > 'conc' avoids the copying, but still traverses the (longer and longer) list each time. To build really long lists it is better to use (make ... (link ...)) ♪♫ Alex -- UNSUBSCRIBE: mailto:picolisp@software-lab.de?subject=Unsubscribe
