Programming Languages Rhys Price Jones Class home page is linked from: http://www.seas.gwu.edu/~rhyspj
Friday, December 31, 2010 CSCI 3221 Programming Languages Rhys Price Jones Class home page is linked from: http://www.seas.gwu.edu/~rhyspj
Friday, December 31, 2010 Textbooks:
Little Schemer absolutely essential to read and write (!) this book this week SICP Structure and Interpretation of Computer Programs a timeless classic buy the paper book, or use the online free version
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Friday, December 31, 2010 Software - free downloads:
Petite chez scheme http://www.scheme.com emacs www.gnu.org/software/emacs You can plug in stuff to Eclipse so it supports scheme but my class presentations and materials will be emacs based
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Friday, December 31, 2010 Platform specifics
Windows nice to have cygwin www.cygwin.com Mac all set to go BUT do not use the Emacs that comes with mac os. Linux ...
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Friday, December 31, 2010 Exams etc
One midterm One final more or less weekly quizzes reading assignments lab assignments
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Friday, December 31, 2010 Overview of course
Learn Scheme Use Scheme Ignore Scheme and concentrate on principles of computation Implement Scheme Modify Scheme Implement other languages
and experiment with language features 6
Friday, December 31, 2010 Reading assignment
linked from class home page This first week. Little Schemer Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5
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Friday, December 31, 2010 This week’s lab
play with scheme What is Scheme? a dialect of Lisp What is Lisp? ...
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Friday, December 31, 2010 Lisp
List Processing Language The “medium of choice for people who enjoy free style and flexibility” Gerald Sussman Invented by John McCarthy 1956 Dartmouth Summer Research Project on AI
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Friday, December 31, 2010 Myths about Lisp
Lots of Irritating Stupid Parentheses Fussy syntax Slow Difficult
Abstruse ab·struse Etymology: Latin abstrusus, from past participle of abstrudere to conceal, from abs-, ab- + trudere to push : difficult to comprehend : re c o ndit e
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Friday, December 31, 2010 Scheme
a “dialect” of Lisp small very close to Lambda Calculus well defined semantics widely available
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Friday, December 31, 2010 How to Program in Scheme
Start it up: type petite in unix shell you’re in an interactive environment whatever you type is a program and gets evaluated My favorite program 2 Another program (+ 2 2) 12 Friday, December 31, 2010 Scheme knows numbers
Try the programs 42 2/4 1.36 -2.0+3i 2/4+3/6i There is a domain of numbers do they mean anything?
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Friday, December 31, 2010 Scheme knows some operations
Try the programs (/ 15 6) (quotient 15 6) (* 3+2i 3-2i) (/ 1 (- 1 (+ (/ 2.0 3) (/ 1.0 3)))) (/ 42 0) There are operations defined on the domain of numbers Do they mean anything? 14 Friday, December 31, 2010 Do they?
Try the programs / quotient sqrt integer? rational? Our domain has numbers and procedures Do they mean anything? 15 Friday, December 31, 2010 Does it matter?
Does it matter if numbers and operations mean anything? In the real world yes In this course no! you’re in a world of your own
www.theflooringcompany.com16
Friday, December 31, 2010 17 www.quackometer.net/.../ humpty-dumpty-795696.gif Friday, December 31, 2010 That’s where we’re going!
The computer will be exactly what we intend No more -- no less We are in control Because we understand semantics!
18 flickr.com/photos/ bobbdobbs/2602758639/ Friday, December 31, 2010