CSE-321 Programming Languages Overview POSTECH March 3, 2009 박성우

2 Neanderthal Man OneTwoThree???

3 Why are two left???Foolish Neanderthal!I can count up to ten! Java Man I got five.I've eaten three.

4 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?"

5 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?

6 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?

7 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

9 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

10 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

11 Dominance of OO TIOBE programming community index, Feb 2009

12 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?

13 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?

15 Commonalities?

16... runs faster on

17 CPU Frequency

18 Multicore Revolution Intel reaches thermal wall, 2004 ) no more free lunch! Intel, 80-cores, 2011 source: Herb Sutter – "Software and the concurrency revolution"

19 Intel Roadmap

20 Tim Sweeney's POPL '06 Invited Talk - Last Slide

3rd Programming Revolution? ) Parallel programming

Course Overview

23 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.

24 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

25 No Cheating Read the document on the disciplinary policy –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.

26 Homework by Thursday Visit the course webpage. – Visit the discussion board. –telnet pl.postech.ac.kr Install –Standard ML –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

27 Make-up Lectures March 2009 Su Mo Tu We Th Fr Sa