CS2403 Programming Languages

Course Outline

Chung-Ta KingDepartment of Computer ScienceNational Tsing Hua University(Slides are adopted from Concepts of Programming Languages, R.W. Sebesta; Modern Programming Languages: A Practical Introduction, A.B. Webber)

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On Valentine’s Day

You want to impress your girl friend by baking a chocolate cake specifically for her.

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Ask the Chef!!!

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巧克力蛋糕食譜 材料：

1/2 杯牛油 約 120 克黑巧克力 兩個雞蛋 兩個蛋黃 1/4 杯砂糖 2 茶匙中筋麵粉

步驟： 預熱烤箱到 230 度。 將巧克力和牛油隔水融化。 攪拌雞蛋、蛋黃和糖至到顏色變淺。 混合巧克力和牛油，倒入蛋液中，加入麵粉，攪拌至完全融合。 把攪拌物倒入模具，放入烤箱烤 6~7 分鐘。 把模具翻轉到盤中，靜置 15 秒後脫模。可配上鮮奶油。

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Chocolate Cake Receipt Materials:

1/2 cup butter 4 ounce bittersweet chocolate 2 eggs 2 egg yolks 1/4 cup white sugar 2 teaspoons all purpose flour

Step: Preheat oven to 450°F. Heat butter and chocolate until chocolate is almost

melted. Beat eggs, yolks and sugar until light colored and thick. Mix chocolate and butter, and slowly pour into egg

mixture, stirring constantly. Stir in flour until just combined.

Pour batter into molds and bake for 6 to 7 minutes. Invert molds on plates, let sit 15 seconds, and unmold. Serve with whipped cream.

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A Receipt Is Like a Program

Receipt: 阿基師 tells you how to

make a chocolate cake Has inputs (butter,

eggs, chocolate, flour, sugar) & output (chocolate cake)

Define a procedure Instruct how

processors (oven, mixer) process inputs to generate output

Can be expressed in different languages

Program: You tell a computer

how to do a computation

Has inputs and outputs

Define a procedure (algorithm)

Instruct how processors process inputs to generate outputs

Can be expressed in different languages

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Questions

Given two languages, how do they differ in expressing the same receipt/algorithm?

Which language is better? How to evaluate “goodness” of languages?

Why are there so many different languages? What is “programming language” anyway? Why does a programming language have so

many different features? How are these features implemented? … Topics of

this course

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A Programming Language Is …

An artificial language designed to express computations or algorithms that can be performed by a computer -- WikipediaA language is a means of expressing your

thoughts to othersIn the case of PL, it is a means of expressing

your thoughts (algorithms) to a computerNatural languages such as Chinese and English

are not used because they cannot be easily translated into machine language executable by the computer 

Keywords: expressiveness, implementation

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Why PL Important?

A language is a framework for problem-solvingIt may facilitate or hinder your thoughts and,

thus, the abilities to solve problemsIt may help you make fewer mistakes

Example: tense and gender, e.g.“He was doing great!” in English

Example: a C language that supports only static and global variables no malloc()How to implement hash table? linked list?

(Ref.: John Mitchell, http://www.stanford.edu/class/cs242)

How to choose

PL?

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Important to Know PL by Trend

(TIOBE Programming Community)

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TIOBE

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Important to Know PL by Trend

Increasing use of type-safe languages: Java, C#, …

Scripting languages for web applications with increasing client-side functionality

More on expressing algorithms than syntax

Runtime environment and virtualization with continuous compilation, analysis, and checking

More program analysis abilities: automated error detection and recovery

(Ref.: John Mitchell, http://www.stanford.edu/class/cs242)

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Important to Know PL by Tradeoffs

Factors influencing programming language Expressiveness:

Application domainsProgramming methods: multiprogramming,

interactive systems,… Implementation: efficiency

Computer architecture, OS, toolchain, libraryEvery convenience has its cost; must

recognize cost of presenting an abstract view of machineUnderstand trade-offs in programming language

design(Ref.: M. Sirjani, http://ut.ac.ir/classpages/ProgrammingLanguages)

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PL as a Course

What is notDo not teach you a programming languageDo not teach you how to program

What isIntroduce fundamental concepts of

programming languagesDiscuss design issues of various language

constructsExamine design/implementation choices for

these constructsCompare design alternatives

Need to be familiar in at least one PL

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Why Study PL?

To improve your ability to develop effective algorithms and to use your languageO-O features, recursionCall by value, call by reference

To allow a better choice of PL Increased ability to learn new languages To make it easier to design a new language To understand significance of

implementationE.g. the efficiency of a recursive function

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Course Information

教授 : 金仲達辦公室 : 資電館 443 分機 : 42804email: king@cs.nthu.edu.tw

助教 :陳志中、劉正芝

上課時間 :週一 13:10–15:00週四 13:10–14:00

上課地點 : CSEE131 http://www.cs.nthu.edu.tw/~king/courses/

cs2403.html

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Textbook

Concepts of Programming Languages, Robert W. Sebesta, 9th Edition, Addison Wesley, 2009Describing Syntax and SemanticsNames, Bindings, and ScopesData TypesExpressions and AssignmentControl StructuresSubprogramsAbstract Data Types, EncapsulationConcurrencyException Handling and Event HandlingFunctional and Logic Programming Languages

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Expected Workload

Assignments:Expect one assignment every two weeks,

including programming assignments

Grade breakdownAssignments 50%Examinations 45%Class participation 5%

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Course Problems

Cannot make examinationsTell us early and we will schedule makeup

Cannot turn in homework on timeNo late homework is accepted

What is cheating?Study together in groups is encouragedWork must be your own