Lecture 21 - November 6, 2007
In
this lecture, different things were covered in the two sections. The 12:30
section spent a lot of time on Snobol and not much time on Lisp. The 2:00 section spent most of its time on
Lisp. Below you will find material from
both sections. You should make sure you
can read and understand and use all of it, regardless of which section you are
in.
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DEFINE('COMB(STR,N,HEAD)CH') :(COMB_END) COMB OUTPUT = EQ(N,0) HEAD :S(RETURN) C2 STR
LE(N,SIZE(STR)) LEN(1) . CH = :F(RETURN) COMB(STR,N - 1, HEAD CH) :(C2) COMB_END COMB('ABCD',3) END |
1 2 3 4 5 6 7 |
Start of hand trace
of function COMB
Variables
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STR |
ABCD |
BCD |
CD |
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N |
3 |
2 |
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HEAD |
NULL |
A |
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CH |
A |
B |
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DEFINE(' R1 ONECH = LEN(1) . CH R2 STRING ONECH =
:F(RETURN) REVERE = CH REVERE :(R2) R_END OUTPUT = REVERE(' END |
Complete hand trace of
VARIABLES
|
STRING |
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iami |
ami |
mi |
I |
null |
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CH |
M |
i |
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a |
M |
i |
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M |
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im |
aim |
maim |
Imaim |
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FUNCTION NAME
LABELS
R1
R2
R_END
PATTERN
ONECH
A possible key for the
Snobol assignment
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DEFINE('LLIST(N)') :(LLIST_END) LLIST OUTPUT = DIFFER(N) VALUE(N)
:F(RETURN) LLIST(LSON(N)) LLIST(RSON(N)) :(RETURN) LLIST_END DATA('BNODE(VALUE,LSON,RSON)') N =
BNODE('+',BNODE('X'), BNODE('Y')) LLIST(N) END |
Slides about LISP produced by former students
LISP
syntax summary produced by
former students - see how helpful you find it
A
Word document discussing some features of LISP
NOTE: Although they exist, we will not
use first, second, nth, loop, do
Below you will
find a giant screen shot showing what the results are of typing various
"things" into the LISP interpreter.
Notice that things which caused errors have been left in so you can see
what doesn't work as well as what works.
Think about why they didn't work.
U:\Web\CS430_~1\Lisp>xlispsml
XLISP-PLUS version 2.1h
Portions Copyright (c) 1988, by David Betz.
Modified by Thomas Almy and others.
> (2 4 6)
error: bad function - 2
> (+ 2 5)
7
> '(2 5 6)
(2 5 6)
> (quote (2 5 7))
(2 5 7)
> quote(2 6 7)
error: unbound variable - QUOTE
> (car '(2 5 7))
2
> (cdr '(2 5 7))
(5 7)
> (car '( (2 3) a (9 2 1))
)
(2 3)
> (cdr '( (2 3) a (9 2 1))
)
(A (9 2 1))
> (FIRST '(2 5 7))
2
> (CADR '(2 5 7))
5
> (CDDR '(2 5 7))
(7)
> (CADDR '(2 5 7))
7
> (CDDDR '(2 5 7))
NIL
> (READ)
APPLE
APPLE
> (SETQ A (READ))
APPLE
APPLE
> A
APPLE
> (setq mylist '(1 2 3 4))
(1 2 3 4)
> (SETQ YOURLIST '(10 11 12 13))
(10 11 12 13)
> yourlist
(10 11 12 13)
> mylist
(1 2 3 4)
> (cons (car mylist) yourlist)
(1 10 11 12 13)
> (cons (cdr mylist) (cdr yourlist))
((2 3 4) 11 12 13)
> (append (car mylist) (cdr yourlist))
error: bad argument type - 1
> (APPEND (CDR MYLIST) (CDR YOURLIST))
(2 3 4 11 12 13)
> (APPEND 3 '(2 5 66))
error: bad argument type - 3
> (APPEND APPLE '(2 5 66))
error: unbound variable - APPLE
> APPLE
error: unbound variable - APPLE
> (APpend a '(2 5 66))
error: bad argument type - APPLE
> (append 'a '(2 5 7 7))
error: bad argument type - A
> (append (list a) (mylist))
error: unbound function - MYLIST
> (append (list a) mylist)
(APPLE 1 2 3 4)
> (defun square (a)
(* a a)
)
SQUARE
> (square 356)
126736
> (defun sum_square (a b)
(+ (* a a) (* b b) )
)
SUM_SQUARE
> (sum_square 2 4)
20
> (trace sum_square)
(SUM_SQUARE)
> (sum_square 2 4)
Entering: SUM_SQUARE, Argument list: (2 4)
Exiting: SUM_SQUARE, Value: 20
20
> (trace +)
(+ SUM_SQUARE)
> (sum_square 2 4)
Entering: SUM_SQUARE, Argument list: (2 4)
Entering: +, Argument list: (4 16)
Exiting: +, Value: 20
Exiting: SUM_SQUARE, Value: 20
20
> (trace *)
(* + SUM_SQUARE)
> (sum_square 2 4)
Entering: SUM_SQUARE, Argument list: (2 4)
Entering: *, Argument list: (2 2)
Exiting: *, Value: 4
Entering: *, Argument list: (4 4)
Exiting: *, Value: 16
Entering: +, Argument list: (4 16)
Exiting: +, Value: 20
Exiting: SUM_SQUARE, Value: 20
20
> (untrace)
NIL
> (sum_square 2 4)
20
> (print 'a)
A
A
> (print a)
error: unbound variable - A
> (round 3.5)
4
-0.5
> (round 3.6)
4
-0.4
> (round 3.2)
3
0.2
> (type-of 7)
FIXNUM
> (type-of 3.6)
FLONUM
> (type-of 7/2)
RATIO
> (type-of 'apple)
SYMBOL