Even less interesting is that this order of evaluation is built into the definition of + rather than being a general facility of the language.
That said, I think "right fold" is available as a feature in most modern lisps (and, of course, if it's not, it's easy to write). -- Raul On Wed, Jul 4, 2012 at 2:50 PM, Devon McCormick <[email protected]> wrote: > I recently discovered interactive Lisp mode in emacs - M-ielm - so I > answered my own question about how Lisp does more generalized > reduction - e.g. with a non-commutative (non-associative) verb like > minus. Unfortunately, it incorporates the less interesting > left-to-right order of evaluation. > > ELISP> (+ 2 3) > 5 > ELISP> (+ 2 3 5 10) > 20 > ELISP> (- 2 3 5 10) > -16 > ELISP> (- 2 3) > -1 > ELISP> (- 2 3 4) > -5 > ELISP> (- 2 3 4 5) > -10 > > On Wed, Jul 4, 2012 at 2:43 PM, Raul Miller <[email protected]> wrote: >> On Wed, Jul 4, 2012 at 2:33 PM, Brian Schott <[email protected]> wrote: >>> Lisp is pretty foreign to me, but I wonder about how to mimic Lisp's >>> postfix (I hope that's the right term for something like "sum(3 2)" if >>> that is actually Lisp syntax)? >> >> Lisp syntax is: >> >> (sum 3 2) >> >> The equivalent J expression would be: >> >> +/3 2 >> >> I think you're getting at the issue of lisp argument passing? If so, >> I can try spelling out what I was trying to say about it. >> >> -- >> Raul >> ---------------------------------------------------------------------- >> For information about J forums see http://www.jsoftware.com/forums.htm > > > > -- > Devon McCormick, CFA > ^me^ at acm. > org is my > preferred e-mail > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
