CS320/13 Functional Programming and Chapter 15
- Look at the [ 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.
- (DEFINE x 10) on page 630 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!
- (CAR Y) is A and
- (CDR Y) is B
We would draw a picture of the memory of the computer like this:
![[ A | B ]](14/ole.gif)
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:
![[ A | -]-->[ B | NIL] [ A | -]-->[ B | NIL]](14/ole1.gif)
In the above diagram
- (CAR Z) is A and
- (CDR Z) is (B . NIL) or (B) for short.
Class Work
[ 13q.html ]
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Preparation
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:
| Page | Function to Trace |
|---|---|
| 638 | member |
| 640 | equal |
| 640 | append |
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 628-644) will work with our
XLISP if you change words as below:
| Page | Scheme | XLISP | Note |
|---|---|---|---|
| 630 | DEFINE | - | OK for functions in our XLISP, but see Note below |
| 631 | EVEN? | evenp | P stands for Predicate |
| " | ODD? | oddp | |
| " | ZERO? | zerop | |
| " | EQV | = | |
| 633 | DISPLAY - | Depends on the precise semantics of DISPLAY, Try one of these | |
| " | " | Prin1 | Print a list of values |
| " | " | Princ | Print a list of values without quoting |
| " | " | Print a list of values on a new line | |
| " | NEWLINE | terpri | terminate print line |
| 638 | #T | t | |
| " | #F | nil | |
| 633 | ELSE | t | |
| 637 | EQ? | eq | |
| " | LIST? | consp | I think. |
| " | ATOM? | atom | |
| " | NULL? | null | |
| 638 | member | Predefined in XLISP | |
| 640 | append | Predefined in XLISP | |
| 643... | mapcar | --Predefined in XLISP |
Note
The XLISP version of DEFINE works for functions not constant terms:. . . . . . . . . ( end of section Preparation) <<Contents | End>>
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