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Week 3  


kbushnel.sdf-us.org/contact.html

Week 3 comments, questions

Course:  Introduction to Lisp on sdf
Instructor:  jgw 
Book:
"COMMON LISP: A Gentle Introduction to Symbolic Computation"
by David S. Touretzky copyright 1990




ANSWERS to the Questions
===============================================
6.10  (defun PALINDROMEP (x) (equal x (reverse x)))
ex:  (PALINDROMEP '(a b c b a))

-------------

6.22 (setf A '(SOAP WATER))

(union A '(no soap radio))=> (soap radio)

(intersection A (reverse A)) => (water soap)

(set-difference A '(stop for water))=>(stop for)

(set-difference A A) => NIL

(member 'soap A) => (SOAP WATER)

(member 'water A) => (WATER)

(member 'washclothe A) => NIL



------------------------------
6.29
length

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6.34
(setf ATLAS 
	((pennsylvania pittsubrgh johnstown)
	 (new-jersey newark princeton trenton)
	 (ohio columbus)))
(defun GET-CITY (x)
	(rest (assoc x ATLAS))

================================================





QUESTIONS about reading material
============================================
pg 164
 example shows:
 
(defun add-to-end (x e)
 "Adds element E to the end of list X."
 (append x (list e)))
(add-to-end '(a b c) 'd) => (A B C D)

   So I just wanted to make sure:  since 'e', defined within defun inputs 
(x e),  makes 'd', of (add-to-end '(a b c) 'd),  a list?  Otherwise if 'd' 
was just appended it wouldn't be a list.  
   Or does 'd' become a list when it's declared as list in (append x (list 
e))) as part of the 'defun' function?

   ---------------------

   pg 164
example shows
> (cons '(here today) '(gone tomorrow))
((HERE TODAY) GONE TOMORROW)
   I'm still not sure where the left parenthesis went that was before 
'gone' i.e '(gone.  

   -------------------------
   
also on pg 164
example shows
> (append '(here today) '(gone tomorrow))
(HERE TODAY GONE TOMORROW)
   Does 'GONE TOMORROW' have a CAR and a CDR?  That's probably obvious 
judging by figure 6.1.

-----------------------

	pg 182  Example showed (quality 'red) => color where element 
queried is (red  .  color).  Why doesn't (quality 'red) => . color, with 
the period,  since the table entry is (red  . color)?
	


=====================================================


COMMENTS 
============================================
Notes;  Interesting the Lisp adds the space to a list.  Example shown:
(append '(friends romans) '(and countrymen))
   No space between 'romans' and 'and' in the append function but it's 
there in the output:
   (friends romans and coutrymen)
    I wonder how this will be used?
	
	-------------------------------
	
	"REMOVE is a non destructive function.  ... The result returned by 
REMOVE is a new list." pg 168
[That's probably significant.]

	-----------------------------------
	
	   Okay!  I tried to do it.  I tried to think in parenthesis, 
which appears to be the most important concept of the 'Introductory' 
Tourtezky instructional method.  However it still eludes me to an extent.   
A dedicated student should apply more focus on CAR, CDR, and Eval 
Notation.
	
	
	Fianally!  Got Clisp and ECL installed on FreeBSD.   MegaPOP 
dialup service didn't update zone files.