CSE-321 Programming Languages
Overview
POSTECH
March 3, 2009
박성우
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Neanderthal Man
OneTwoThree???
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Why are two left???Foolish Neanderthal!I can count up to ten!
Java Man
I got five.I've eaten three.
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Language = Frame of Thought• The language defines the frame of thought.
– what you can communicate to others– what concepts you are able to think over– how you think
• Big question:
"Does the programming language define the frame of thought in the course of programming?"
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C Exercise: Integration• Specification
– input: function f from int to int range a and b
– output: f(a) + f(a + 1) + ... + f(b)
• Solution?int integral(int (*f)(int), int a, int b) {
int i, sum = 0;for (i = a; i <= b; i++)
sum += f(i);return sum;
}
• Question: what if there were no function pointer?
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C Exercise: Derivative• Specification
– input: function f from float to float– output: derivative f' of f such that
f'(x) = (f(x + ) - f(x)) /
• Solution?
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Question for You• What is your favorite language?
– Assembly, Basic, Pascal, C, C++, C#, Java, Perl, Python, Ruby, Prolog, Lisp, SML, Haskell, Scheme, ...
• What is its strength?• What is its weakness?• What is its limitation?
• Do you think your language defines the frame of thought?
Trends in programming language research
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Structured Programming• Features
– split programs into sub-sections (e.g., functional units) and reuse the sub-sections
• procedural programming– limited number of control structures
• for, while, do/while, repeat/until• goto is discouraged.
• Pascal, Ada, C, ...• Enabled the development of large-scale software in 1970s
– Unix operating system written in C– 1st revolution in programming language history
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Object-oriented Programming• Features
– focus on objects, rather than operations– hide the internal representation of an object– code reuse by inheritance or subclassing
• Smalltalk, C++, Java, C#, ...• Enabled the cooperative development of large-
scale software in 1980s– 2nd revolution in programming language history
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Dominance of OO• TIOBE programming community index, Feb 2009
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Limitation of OO Programming• No code reuse for different datatypes
– templates in C++– generics in Java
• No "first-class" functions– closures in Java
• No inherent support for modular programming– Classes are okay for modular programming of
moderate scale.– OO does not scale afterwards. Why?
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Functional Programming• Standard ML, Haskell, Objective CAML, F#, ...• Savior for OO programming
– templates in C++, generics in Java) primitive forms of polymorphism in type theory
– closures in Java) functions in functional programming
– modular programming) structures and functors in functional programming
• F# to be included in Microsoft Visual Studio 2009
What is the (ongoing) 3rd revolution in programming
language history?
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Commonalities?
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... runs faster on
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CPU Frequency
http://www.tomshardware.com/reviews/mother-cpu-charts-2005,1175.html
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Multicore Revolution
• Intel reaches thermal wall, 2004 ) no more free lunch!
• Intel, 80-cores, 2011
source: Herb Sutter – "Software and the concurrency revolution"
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Intel Roadmap
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Tim Sweeney's POPL '06 Invited Talk- Last Slide
3rd Programming Revolution?
) Parallel programming
Course Overview
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Topics to Be Covered• Basic programming language theory
– inductive reasoning– -Calculus– basic type theory– modular programming (assignment)– object-orientation (lecture, assignment)
• Parallelism/concurrency will not be covered.
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Grading• 50% assignments (heart of this course)
– 8 programming assignments, all in Standard ML• 10% quizzes
– 4 quizzes (substitute for written assignments)• 20% midterm• 20% final
• Optional track: 40% project– Building a compiler for a small functional language.– Details will be announced before the midterm.
• Absolute grading system
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No Cheating• Read the document on the disciplinary policy.
• 2006– 7 students cheated (out of 46 students)– 2 suspicious cases
• We will check your programs at the end of the semester.– all your programs + those submitted in the previous years
• Cheating will not be tolerated.– Cheating will expel you from class and get you an F.
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Homework by Thursday• Visit the course webpage.
– http://www.postech.ac.kr/~gla/cs321/• Visit the discussion board.
– telnet pl.postech.ac.kr• Install
– Standard ML 110.58.– AFS client software.
• Read three articles for fun.– A Critical Look at Programming Languages– The Free Lunch is Over: A Fundamental Turn Toward
Concurrency in Software– Software and the Concurrency Revolution
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Make-up Lectures March 2009
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