Why do you want to avoid foreach which happens to cater for your needs? Just write a simple wrapper (I'll call it apply$) and use it just like (apply):
; a function to be called on each element of a list (deffunction show (?x) (printout t "show: " ?x crlf) ) ; (apply$ <function> <expression>*) ; calls 1st argument for each successive argument, ; flattening list arguments (deffunction apply$ (?func $?list) (foreach ?el $?list (apply ?func ?el)) ) ; example for calling apply$ (bind ?alist (create$ foo bar blech)) (apply$ show ?alist) Regards Wolfgang JKBM wrote:
I was wondering if there was any way to call a function on a variable containing a list without having to use a foreach/while loop. (apply + 1 2 3) obviously works, but (apply + (create$ 1 2 3)) doesn't, so that doesn't help me. This sort of problem comes up a lot, and I usually handle it by implode$-ing the list, str-cat-ing the function and parentheses, and then build-ing it as follows: (bind ?list (create$ 1 2 3)) (apply + ?bind) ;ERROR, as mentioned above (build (str-cat "(+ " (implode$ ?list) ")) ;SUCCESS However, this time, I'm dealing with a list of fact-ids, and this method doesn't work because Jess doesn't parse "<Fact-2>" to a fact-id from the implode$-ed string. I thought maybe I could create$ a new list with the function at the beginning, but there is no way that I could find to evaluate a list, only a string. E.g.: (bind ?list (create$ 1 2 3)) (bind ?flist (create$ + ?list)) ;?flist is (+ 1 2 3), but can't evaluate So, I guess I'm looking for three possible solutions: 1) calling a function on a list 2) getting Jess to correctly parse a fact-id from a string 3) getting Jess to evaluate a list as a function Any ideas? Or should I just give up and resort to iterative measures? -- View this message in context: http://www.nabble.com/Calling-a-function-on-all-elements-in-a-list-tp15921074p15921074.html Sent from the Jess mailing list archive at Nabble.com. -------------------------------------------------------------------- To unsubscribe, send the words 'unsubscribe jess-users [EMAIL PROTECTED]' in the BODY of a message to [EMAIL PROTECTED], NOT to the list (use your own address!) List problems? Notify [EMAIL PROTECTED] --------------------------------------------------------------------
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