Scheme Programming Language :: how do they do variable length arguments in the old days?


	how do they do variable length arguments in the old days? hi how do they do variable length arguments in the old days? (using only lambda) I don't think it's possible in the really old days, they probably just used a single list... ;; this seems to be the new syntax with the dot (define sum (lambda (x . y) (apply + x y))) (sum 1 2 3 4 5) my toy interpreter can't handle this after I've been tweaking it for one day. I'm sorta giving up. new interpreters can do this weird thing: ((lambda x (cons x 'b)) 'a) , which is different from ((lambda (x) (cons x 'b)) 'a) strange... dillog@gmail.com wrote: > how do they do variable length arguments in the old days? (using only > lambda) > [...] > ;; this seems to be the new syntax with the dot > (define sum (lambda (x . y) (apply + x y))) > (sum 1 2 3 4 5) This is in fact the syntax using "only lambda". You could also write (define (sum x . y) (apply + x y)). > ((lambda x (cons x 'b)) 'a) , which is different from ((lambda x x)) => () ((lambda x x) 1) => (1) ((lambda x x) 1 2) => (1 2) ... See the pattern? > ((lambda (x) (cons x 'b)) 'a) ((lambda (x) x)) => wrong! ((lambda (x) x) 1) => (1) ((lambda (x) x) 1 2) => wrong! (define (f . x) ...) = (define f (lambda x ...)) -- Nils M Holm <n m h @ t 3 x . o r g> -- http://t3x.org/nmh/ dillog@gmail.com writes: > hi > how do they do variable length arguments in the old days? (using only > lambda) > I don't think it's possible in the really old days, they probably just > used a single list... That's was possible in the really old days. They just used a single list. Check the sources in http://www.informatimago.com/develop/lisp/lisp15-0.0.tar.gz search for: APPLY(F,L,A) -- __Pascal Bourguignon__ http://www.informatimago.com http://pjb.ogamita.org