1. CSE 415 -- (c) S. Tanimoto, 2002 Introducing Lisp
Introducing Lisp The dominant programming language for experimental AI systems
Lisp strengths:
Interactive
Supports symbolic computation
Programs and data share a common representation
Automatic management of memory
Simple syntax
Multiparadigm (functional, imperative, object-oriented)
Supported by a long history and wide literature
Also used as an internal scripting language for Gnu Emacs, Autocad, and other packages.
CSE (c) S. Tanimoto, Introducing Lisp

2. CSE 415 -- (c) S. Tanimoto, 2002 Introducing Lisp
LISP = LISt Processing
Intended for processing symbolic information
Implementations from noncommercial sites:
GNU Common Lisp (GCL) - U of Texas mods to Kyoto Common Lisp
CLISP -- developed in Germany.
Available implementations from
Allegro Common Lisp for Windows, Web edition.
Allegro Common Lisp for Linux
CSE (c) S. Tanimoto, Introducing Lisp

3. CSE 415 -- (c) S. Tanimoto, 2002 Introducing Lisp
LISP: Our Objectives
Motivation and History
Interactive programming
Functional programming
List manipulation with recursive functions
Language extensibility via macro definitions
Language evolution to support multiple paradigms
Lisp look and feel
Lisp for rapidly prototyping AI systems
Lisp on the Web
CSE (c) S. Tanimoto, Introducing Lisp

4. History of Lisp (continued)
John McCarthy, developed the ideas during the Dartmouth Summer Research Project on Artificial Intelligence, 1956.
First implementation on the IBM 704
John McCarthy published “Recursive functions of symbolic expressions and their computation by machine” in Communications of the Association for Computing Machinery in 1960.
CSE (c) S. Tanimoto, Introducing Lisp

5. History of Lisp (continued)
1970s: advanced dialects -- MacLisp, InterLisp;
Lisp machines (Symbolics, Inc.; Lisp Machines, Inc.; Xerox; Texas Instruments)
Late 1970s: Scheme, Portable Standard Lisp, XLISP.
1984. Common Lisp.
Use of Lisp as internal scripting languages: Gnu Emacs, AutoCAD.
1987 CLOS = Common Lisp Object System.
1994 ANSI Standard Lisp.
CSE (c) S. Tanimoto, Introducing Lisp

6. CSE 415 -- (c) S. Tanimoto, 2002 Introducing Lisp
Interacting with Lisp
Interaction takes place in a Lisp Listener Window.
Lisp runs an endless loop for interacting with the user:
READ
EVAL
PRINT
CSE (c) S. Tanimoto, Introducing Lisp

7. Interacting with Lisp (continued)
> (+ 3 5) 8
> (* 2.5 (+ 2 2))
10.0
> (setq x 5) 5
> (sqrt x)
> (* x x) 25
CSE (c) S. Tanimoto, Introducing Lisp

8. CSE 415 -- (c) S. Tanimoto, 2002 Introducing Lisp
Defining a function
> (* 5 5 5)
125
> (defun cube (n) (* n n n))
CUBE
> (cube 2) 8
> (cube )
CSE (c) S. Tanimoto, Introducing Lisp

9. CSE 415 -- (c) S. Tanimoto, 2002 Introducing Lisp
Symbolic Values
Symbols are like identifiers, but they are commonly used as values as well as variables.
> (setq x ’pizza)
PIZZA
> x
> (setq pizza ’pepperoni)
PEPPERONI
> pizza
> (eval x)
CSE (c) S. Tanimoto, Introducing Lisp

10. More on Evaluation of Symbols
> (setq x ’y) Y
> (setq y ’z) Z
> (setq z ’x) X
> x
> (eval x)
> (eval (eval x))
CSE (c) S. Tanimoto, Introducing Lisp

11. CSE 415 -- (c) S. Tanimoto, 2002 Introducing Lisp
Values of Symbols
A symbol without a value in the current context is said to be “unbound”.
The value of a symbol can be any Lisp object, including a number, another symbol, a functional object, a list, and array, etc.
A symbol can have several local (“lexical”) values and one global value. However, symbols belong to “packages”, and two different packages can have symbols with the same name.
CSE (c) S. Tanimoto, Introducing Lisp