Transcript lisp programming

Lisp Laboratory
gcLisp (Golden Common Lisp)
The history of Lisp
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In summer 1956, Allen Newell, J.C. Shaw, and
Herbert Simon had developed “list processing” and
created IPL (Information Processing Language),
abstract for manipulated symbols and list.
When FORTRAN had build, McCarthy designed a
new languae, LISP ( List Processor), drew on idea
from IPL, FORTRAN and FLPL, run on IBM704
In the 1970s Guy Steele and Gerald Sussman
defined Scheme, combined Algol and Lisp.
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The history of Lisp
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By the early 1980s, there were dozens of
incompatible Lisp.
A project to define a Common Lisp that would merge
the best feature of existing dialects into a coherent
whole.
The first edition of the Common Lisp standard
appeared in 1984.
Many idea in programming systems such as
interpreted and compiled function, garbage
collection, recursive function calls, source-level
tracing and debugging, and syntax-directed editors.
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Installation
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Download GC-Lisp from web of course
Double click for unzip file
Extract at “C:\”
Appear dialog, creating folder “C:\GCLisp”
Answer OK
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Startup gclisp
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Click start bottom and click run and type, or
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Double Click Gclisp.exe for loading in
“C:\gclisp” directory
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GC-LISP Environment
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You will see window of GCLISP as
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Some Command:Hot Key
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<Alt>-H
<Alt>-E
<Ctrl>-E
<F1>
<F8>
<F9>
<F10>
to get help
to enter the LISP Explorer
to enter the editor
to exit editor into Lisp Environment
to load a file into the editor
to save a file
to save a file as another name
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Command line
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Type these command follow symbol “*”
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Prefix command
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All command is in parentheses ( )
It will evaluate when we type “)”
Command form in term prefix
(function <paramete>)
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GMAC editor window
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Press <Ctrl>-E for getting GMAC editor
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<F9> to save file and <F1> back gcLisp
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Load file into gclisp
environment
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Load first.lsp
* (load ‘first)
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Functions and data
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The term data means information such as
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Numbers
Words
Lists of things
The function operates on the data in some
way and the result is output
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Functions Box
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Function on Data
data
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Function
+
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result
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A table function in lisp
+
*
/
ABS
Adds two numbers
Subtracts the second from the first
Multiplies two nubmers
Divides the first by the second
Absolute value of a number
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SYMBOLs
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Symbols are another type of data in Lisp
It is more interesting than numbers
Symbols are named
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English words
Phrases
Common abbreviations
Symbol may be letters, number, and special
characters such as hyphen(-)
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EXERCISE
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Following : symbol or number
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AARDVARD
87
1-2-3-GO
3.12
7-11
22/7
-12
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THE SPECIAL SYMBOLs
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Two Lisp symbols have special meaning
attached to them.
T
Truth, “yes”
NIL
Falsity, emptiness, “no”
***NIL can express by ( )
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Some Predicate
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A predicate is a question-answering function
(likely yes-or-no question)
Two predicate :
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NUMBERP (number predicate) to check whether
expression is number
SYMBOLP (symbol predicate) to check whether
expression is symbol
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Test Predicates
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Type following this screen
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More Predicates
ZEROP
ODDP
EVENP
<
>
EQUAL
NOT
to check zero
to check odd number
to check even number
to compare first < second
to compare first > second
to compare first = second
to opposite
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Test Predicate
*
*
*
*
*
*
*
*
*
*
(ZEROP
0)
(ZEROP
5)
(ODDP
1)
(ODDP
2)
(EVENP
1)
(EVENP
2)
(< 2 1)
(> 2 1)
(EQUAL 1 (- 3 2))
(NOT NIL)
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Set variable
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Binding free variables
Sets variable to the value or the expression
by
(setq variable <expression>)
* (setq x 5)
* (setq a ‘(1 2 3 x y z))
* (setq b ‘(red green blue))
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Lists
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LISP is named from LISt Processor
Lists are central data type, the most versatile
data type
Lists are important because they can be
made to represent practically anything: sets,
tables, and graphs and even English
sentences.
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Example of Lists
(RED
GREEN
BLUE)
NIL
RED
GREEN
BLUE
(2 3 5 7 11 13 17 19)
(Lisp is powerful)
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NESTED LISTs
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A list may contain other lists as elements
Given the three lists
(BLUE SKY)
(GREEN GRASS)
(BROWN EARTH)
Make list that consists of the above lists
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((BLUE SKY) (GREEN GRASS) (BROWN EARTH))
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LENGTH OF LISTs
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The length of a list is the number of elements
it has
(LENGTH <LIST>)
*
*
*
*
(setq x
(LENGTH
(setq a
(LENGTH
‘(HI MOM))
x)
‘((blue sky) (green grass) (brown earth)))
a)
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Exercise
How many elements of following lists have?
(OPEN DOOR PLEASE)
(OPEN (THE DOOR) PLEASE)
((1 2) (2 3) (3 4) (4 5) (5 6))
((ONE) FOR ALL (AND (TWO (FOR ME))))
(A (B C) D ())
(A B (C D) ())
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Construct of List
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We have three function to make list
(cons <exp> <exp>)
(list <exp> <exp>)
(append <exp> <exp>)
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Constructing Lists
Using ‘cons’
 (cons ‘(a b) ‘(c d))
((A B) C D)
Using ‘append’
 (append ‘(a b) ‘(c d))
(A B C D)
Using ‘list’
 (list ‘(a b) ‘(c d))
((A B) (C D))
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Make List Example
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Type and look the result
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Element order in list
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In list are considered into two part : head and
tail
a
head
(b c d)
tail
(a b c d)
CAR is function to get head part of list
CDR is function to get tail part of list
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Result of car & cdr
* (setq a ‘(x y z))
* (car a)
* (cdr a)
* (setq b ‘((blue sky) (green grass) (brown earth)))
* (car b)
* (cdr b)
* (caar b)
* (cadr b)
* (cdar b)
* (cddr b)
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Meaning function c?r
(caar x)
(cadr x)
(cdar x)
(cddr x)
(caadr x)
(caddr x)
(cdddr x)
-
(car (car x))
(car (cdr x))
(cdr (car x))
(cdr (cdr x))
(car (car (cdr x)))
(car (cdr (cdr x)))
(cdr (cdr (cdr x)))
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Creating Function
The syntax for creating function as:
(defun <FunctionName> (parameter-list)
<function body>)
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Example Function
Look this example
(defun call-up (caller callee)
(list ‘hello callee ‘this ‘is caller ‘calling))
* (call-up ‘FRED ‘WANDA)
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Example Function
Look this example
(defun double (n)
(* n 2))
* (double 2)
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Example Function
(defun absolute-value(x)
(cond ((< x 0) (- x))
((>= x 0) x)))
(defun absolute-value(x)
(cond ((< x 0) (- x))
(t
x)))
(defun absolute-value(x)
(if (< x 0) (- x) x))
* (absolute-value 2)
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Conditionals(1)
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Its form as:
(cond
(<condition1> <action1>)
(<condition2> <action2>)
……..
(<conditionN> <actionN>))
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Conditionals
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Its form as:
(if <test> <then-action> [<else-action>])
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Some predicates for condition test:
= > < >= <=
oddp evenp numberp minusp zerop plusp
member atom listp null equal and or not
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Recursive Functions
(defun my-member(element list)
(cond ((null list) nil)
((equal element (car list)) list)
(t (my-member element (cdr list)))))
(defun my-length(list)
(cond ((null list) 0)
(t (+ (my-length(cdr list)) 1))))
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Recursive Functions
(defun count-atoms(list)
(cond ((null list) 0)
((atom list) 1)
(t (+ (count-atoms (car list))
(count-atoms (cdr list))))))
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Linear or cdr recursion
(length ((1 2) 3 (1 (4 (5)))))
3
+
1
(length (3 (1 (4 (5)))))
+
1
(length ((1 (4 (5)))))
+
1
(length ())
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Tree of recursion
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Side Effects
*(defun f(x)
(setq inc (+ inc 1))
(+ x inc))
*(setq inc 0)
*(f 4)
*(f 4)
*inc
*x
*(defun foo(x)
(setq x (+ x 1))
x)
*(setq y 1)
*(foo y)
*(foo y)
*y
*x
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