main shared4 parbegin p1 p2 parend print shared

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main() shared4 parbegin p1() p2()
parend print shared
Quiz

• p1()
• shared shared 2

• p2()
• sharedshared2

What is the output of the concurrent program
shown above?
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Items Due

• Homework 7 is due (Friday)
• Homework 8 is due (Friday)
• You may come and talk to me about your draft for
  HW 8

3
Course Summary
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Study programming languages Why?

• Use of existing languages
• Vocabulary of useful programming constructs
• Better choice of programming languages
• Ease of learning new languages
• Ease of designing new languages

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Study programming languages How?

• Grand Tour
• Learn different languages, C, C, Java, Lisp,
  etc.
• Languages become obsolete and new languages are
  designed all the time.
• Principles
• Learn the underlying principles, vocabulary,
  structure and meaning
• More enduring

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If you give a man a fish he will have a single
meal. If you teach him how to fish, he will eat
all his life. Kuan-tzu (Chinese Philosopher)
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Design Principles

• Syntax
• What is a correctly written program?
• What are the basic building blocks?
• Vocabulary of words
• What rules guide how the words are put together
  to make a correct program?
• Context-Free Grammars

8
Design Principles

• Type systems and Semantics
• What does a program/fragment/construct mean?
• Important for program correctness.
• Formal approaches are need to answer this
  systematically.

9
Design Principles

• Memory Management
• How do the program elements map to physical
  memory?
• Variables, data structures
• Function call, recursion
• Static and dynamic memory
• Dynamic memory management
• Objects have definite life spans
• Garbage collection
• Essential to have an understanding

10
Design Principles

• Exception Handling
• How does a program prepare for unexpected events
  during its execution?
• Division by zero
• Improper/illegal input
• Exceptions
• Programs must trap exceptions and provide
  alternative paths or graceful exit.

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Programming Paradigms

• Many different languages
• Only a few different styles of programming
• Imperative Programming
• Object-oriented Programming
• Functional Programming
• Logic Programming
• Event-Driven Programming
• Concurrent Programming

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Imperative Programming

• Program is a series of steps
• Retrieves input
• Perform some computation
• Generates output
• Essential building blocks
• Assignments
• Procedures
• Control structures
• Examples Fortran, C, Cobol

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Object-oriented Programming

• Program is a collection of objects
• Interaction between objects is via message
  passing
• Essential building blocks
• Object modeling
• Inheritance
• Examples C, Java, Smalltalk

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Functional Programming

• Program is a collection of mathematical functions
• Have one or more arguments
• Return a value
• Essential building blocks
• Composition
• Recursion
• Examples Lisp, Scheme, ML

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Logic Programming

• Program is a collection of logical declarations
• Separation of logic (what) and control (how)
• Natural choice to express non-determinism
• Examples Prolog

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Event-Driven Programming

• Program is a continuous loop
• Wait for some event
• Respond to the event
• Order of event is arbitrary
• Increased attention due to GUIs
• Examples Visual Basic, Java

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Concurrent Programming

• Program is a set of cooperating processes
• Each process works on its own
• Shares information with others from time to time
• Essential building blocks
• Parallel constructs
• Examples Linda, High Performance Fortran (HPF)

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Goals of this course

• Formal approach to language design
• Careful examination of key programming paradigms
• Hands-on programming experience
• I hear
  and I forget!
• I see and I remember!!
• I do and I
  understand!!!
• 
  (Chinese proverb)

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• No class on Friday.
• Final grades will be posted on the Blackboard!
• Good luck in the finals!!
• Happy Holidays!!!