set - setf - setq woes

[dukester]

I'm getting back to playing with newLISP!  - Again!!  :)

The following code broke when I used setf or setq!  Why is that?  What is the subtle diffs between the three?  I want to grok this ASAP - so that I don't spin my wheel ever again with setting a symbol, etc.  TIA

Code Select Expand


(set 'vowels '("a", "e", "i", "o", "u"))

;; define a function called pig-latin

(define (in-pig-latin this-word)
(set 'first-letter (first this-word))
(if (find  first-letter vowels)
(append this-word "ay") ; concatenate word and "ay"
(append (slice this-word 1) first-letter "ay")))  ; concatenate

;; test the function

(println (in-pig-latin "red"))
(println (in-pig-latin "orange"))
(exit 0)

;; output is
;;edray
;;orangeay

;;Notes:  the setf and setq function BROKE the code when I tried to use them
;;  Why was that?  When is setf and setq used in NL?


[rrq]

Hmm, did you have the variable quoted maybe?

[dukester]

Hmm, did you have the variable quoted maybe?

Are you asking if I used setf/setq and quoted the symbol as well?  I'm not sure ...  :/



Regardless of how I screwed up though (and I did) ,  I'm looking for extra simple directions as to when to use 'set' , 'setf' and 'setq' so that I won't go down that road ever again! :D

[vetelko]

Description in manual is short and simple

http://www.newlisp.org/downloads/newlisp_manual.html#setf">//http://www.newlisp.org/downloads/newlisp_manual.html#setf

[dukester]

Description in manual is short and simple

http://www.newlisp.org/downloads/newlisp_manual.html#setf">//http://www.newlisp.org/downloads/newlisp_manual.html#setf

I did  RTFM !!  Examples with extra skinny explanations !  Thanks anyway!  +1

[varbanov]

Hi,



Shortly, set is a "classical" function - it evaluates its arguments. That's why you quoted vowels - to prevent evaluation.



setq and setf are synonyms in NewLisp. The names are inherited from other (Common) Lisps.

They are "special forms".

If the first argument is a symbol, the value of the evaluated second argument is assigned directly to that symbol, without evaluating the first argument.

Otherwise, the first argument is evaluated and if the result is a valid reference, the second argument value is destructively assigned to the place, where the reference points.



s.v.

[dukester]

@s.v.   Thanks!  I will read your reply carefully and as an exercise, I will fabricate some examples to prove your points.



I have been using (set 'a-symbol blah blah) as an equivalent to (setq a-symbol blah blah).  Maybe that was a bad assumption!



Thx for the input ...