.Open CS320/13 Functional Programming and Chapter 15
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.Row Prev 12	Implementing subprograms        Chapter 10  but not  10.3.4.2   lab12 LISP102
.Row 13	Functional  Programming	Chapter 15  not section 8       lab13 LISP103
.Row Next 14	Data  Abstraction       Chapter 2  section 14 +  Chapter 11     lab14 C/C++ ADTs
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.Open Preparation 
.List
 Look at the 
.See Supplement to Chapter 15
below.
 Study chapter 15 but not sections 15.7 and 15.8.
 Think about chapter 15 and try the Extra Exercises below.
 Answer the chapter's review questions (ignore questions on
ML and Haskell)
 Hand in answers 3 or more review questions at the start of
class.
.Close.List

. Supplement to Chapter 15

I am likely to ask you to program a simple LISP function in the final. 
These are the kinds of functions that are examples in section 15.5.5 or 
solutions to one or more the first 5 Problems at the end of the chapter. We
will practice functions like these in the next class and in the lab.

. Extra Exercise
Invent a test case and trace, step by step, what the following functions do
according to their definitions in the book:

.Table Page	Function to Trace
.Row 660	member
.Row 661-2	equal
.Row 662	append
.Close.Table

You can try them out and TRACE them on our computers using XLISP, as long
as you translate them.

. Translation (Book -> Lab)
Nearly all of the book's Scheme examples(pages 650-666) will work with our
XLISP if you change words as below:

.Table Page	Scheme	XLISP	Note
.Row 652	DEFINE	-	OK for functions in our XLISP, but see $Note below
.Row 653	EVEN?	evenp	P stands for Predicate
.Row "	ODD?	oddp
.Row "	ZERO?	zerop
.Row "	EQV	=
.Row 653	DISPLAY -	Depends on the precise semantics of DISPLAY, Try one of these
.Row "	"	Prin1 	Print a list of values
.Row "	"	Princ 	Print a list of values without quoting
.Row "	"	Print 	Print a list of values on a new line
.Row "	NEWLINE	terpri		 terminate print line
.Row 654	#T	t
.Row "	#F	nil
.Row 655	ELSE	t
.Row 658	EQ?	eq
.Row 659	LIST?	consp	I think.
.Row "	ATOM?	atom
.Row "	NULL?	null
.Row 660	member	Predefined in XLISP
.Row 661	append	Predefined in XLISP
.Row 665...	mapcar	--Predefined in XLISP
.Close.Table
. Note
The XLISP version of DEFINE works for functions. It will not define constant terms:
   (DEFINE x 10) on page 652 must be translated to
 (SETQ x 10).

To get the static scoping use the `defun` operator: 
 (DEFUN name (args) expression)
in place of
 (DEFINE (name args) expression) 
Notice how the 
parentheses move when you shift from Scheme to XLISP!
.Close Preparation 
. Reminders about LISP
LISP makes data structures using dotted pairs. A dotted pair is an object 
with two parts called: CAR and CDR.

If Y has value (A . B) (notice the dot), then
              (CAR Y) is A
and
        (CDR Y) is B

We would draw a picture of the memory of the computer like
this:
.Image 14/ole.gif [ A | B ]

If Z is a variable that has a simple list (A B ) (notice the absence of a 
dot between A and B!) then the
B is in a second dotted pair, linked to the first one like this:
.Image 14/ole1.gif [ A | -]-->[ B | NIL] [ A | -]-->[ B | NIL]
In the above diagram
              (CAR Z) is A
and
              (CDR Z) is (B . NIL) or (B) for short.
. Class Work
.See ./13q.html
.Close
. Lab Work
.See ./lab/13.html
. Next
.See ./14.html