강의 내용 및 방법 접근방법 시험 수업은 75분(14:30-15:45), 혹시 부족하면 보강 Proof of Correctness는 제외 Lambda Calculus: Python과 관련하여 조금 설명 리포트 2주일에 프로그램 1개 정도, term project는 없음, 각 장의 문제풀기 및 다른 문제 제공 시험 중간, 기말 및 1~2회 정도의 쪽지시험 수업은 75분(14:30-15:45), 혹시 부족하면 보강

참고자료 Http://borame.cs.pusan.ac.kr/lecture 강의참고자료 (한글) 2002년 강의 내용 2002년 리포트, 기타 참고사항 2003, 2004, 2005, 2006, 2007, 2008, 2009년, 2010, 2011, 2012년 강의노트 다른 대학교, 자료, 우균 교수 자료(한글) 참고 강의 중에 이해가 안 되는 부분은 언제나 홈페이지의 묻고 답하기에 질문할 수 있음

프로그램 개발 어떻게 하면 프로그램 개발과 유지보수 비용을 줄이느냐? 프로그램에서 재사용할 수 있는 부분과 아닌 부분을 나누어서 개발하고, 재사용을 극대화 (개인별 라이브러리 보관) 많은 라이브러리를 보유하고 활용 high-level data types built in, such as flexible arrays and dictionaries 그러면서 어떻게 하면 메모리 사용량을 줄이고, 속도를 높이느냐? Runtime checking을 최소화

프로그래밍 언어, 어떤 것을 쓰나? Paul Graham은 "Revenge of the Nerds"와 "Beating for average"에서 언어의 관성을 언급하면서, 익숙해지면 그 언어의 틀 속에서 자신의 생각을 가두게 되어 편견에 사로잡혀 언어의 활용을 효과적이지 못하게 된다면서, 익숙한 언어보다는 적합한 프로그래밍 언어를 선택할 줄 알아야 한다고 했죠. 즉, 최소한 몇 가지 언어를 알고 자신의 업무에 적합하게 사용할 줄 알아야 한다는 말입니다. GitHub: JavaScript, Ruby, Python, PHP, Java, C#, C, Perl, C++, Objective C StackOverflow: C#, Java, PHP, JavaScript, C++, Python, Objective-C, C, Ruby, Perl, Delphi

프로그래밍 언어 사용 빈도 (Script 언어 제외) Tiobe.com (Skilled Engineer) Java – 19.1% C – 15.2% C++ – 10.1% PHP – 8.7% Visual Basic – 8.4% Perl – 6.2% Python – 3.8% C# – 3.7% JavaScript – 3.1% Ruby – 2.6% Delphi – 2.1% Dice.com (2006년) Java – 35.7% C, C++ – 15.3% C# – 12.7% Perl – 11.9% JavaScript – 10.9% Visual Basic .NET – 5.2% PHP – 2.9% Ajax – 2.7% Python – 2.0% Ruby – 0.7%

왜 프로그래밍 언어론을 배우나? 수많은 프로그래밍 언어 중 필요에 따라 적합한 것을 골라 쓸 수 있는 능력 사용하는 프로그래밍 언어의 특성을 파악하여 가장 효과적으로 사용할 수 있게 함 사용하는 프로그래밍 언어에 없지만 유용한 개념을 도입하여 활용 프로그래밍 언어 그 자체로도 의미가 있음

언어란? 생각을 표현하는 도구!! 정보를 교환하는 도구!! 개념화 : 물체(Object), 물체와 관계, 추상화 중력의 법칙, 예측 인간은 전체를 듣지 않고도 부분을 이해함, 스스로 보완하여 인식함 불완전하며 모호함 프로그래밍언어 !! 우리의 생각을 컴퓨터가 처리할 수 있게 표현하는 도구 조금만 틀려도 이해 못함(수학적 명확성 필요) 오류가 없는 프로그램은 만들 수 없으며, 인간이 1,000만 줄 이상 프로그램은 만들 수 없다. (조던 폴락) 기계와 인간 간의 간격을 줄일수록 바람직함 추상화 단계가 높아져야 짧은 프로그램을 명확한 프로그래밍이 가능 기계뿐 아니라 인간도 이해해야 함 (쉽게 프로그램할 수 있어야)

Organization of Programming Languages Understand how languages are designed and implemented 구조 Lexicon – What sorts of words are legal? Syntax -- What a program looks like? Semantics -- What a program means? Pragmatics – 실행 과정에서 해석? C언어의 ‘int’형 가장 기본 단위 문법요소, 단어, 고유명사 등 명칭 문법요소, keywords, 명칭 기본요소가 결합하는 방법 결합한 요소의 뜻 파악 Implementation -- How a program executes

프로그래밍 언어의 모형 Understand most appropriate language for solving specific problems, For example: Pascal, C, Perl -- procedural, statement oriented C++, Java, Smalltalk -- Object oriented ML, Lisp -- Functional Prolog -- Rule-based JavaScript, PHP, ASP.net, C# – Procedural, Event-driven accessing

Language Goals During 1950s--1960s - Compile programs to execute efficiently. There is a direct connection between language features and hardware - integers, reals, goto statements Programmers cheap; Machines expensive; Keep the machine busy But today Compile programs that are built efficiently CPU power and memory very cheap Direct connection between language features and design concepts - encapsulation, records, inheritance, functionality, assertions Event-driven programming, Service-oriented approach, Web-service, Very High-level Language

Python Python is a general-purpose, high-level programming language. Its design philosophy emphasizes programmer productivity and code readability. Python's core syntax and semantics are minimalist, while the standard library is large and comprehensive. Python supports multiple programming paradigms (primarily functional, object oriented and imperative), and features a fully dynamic type system and automatic memory management; it is thus similar to Perl, Ruby, Scheme, and Tcl. Python was first released by Guido van Rossum in 1991.[3] The language has an open, community-based development model managed by the non-profit Python Software Foundation. While various parts of the language have formal specifications and standards, the language as a whole is not formally specified. The de facto standard for the language is the CPython implementation.

Why study programming languages? (1) To improve your ability to develop effective algorithms Improper use of recursion Object-oriented programming, logic programming, concurrent programming To improve your use of your existing programming language Data structures for arrays, strings, lists, records, set, bag, table (associative array) Malloc()  garbage collection Implementation details of recursion, object classes, subroutine calls, exception(event) handling … Service-oriented developing Web-service, Semantic web, Script language

Why study programming languages? (2) To increase your vocabulary of useful programming constructs Increase programming vocabulary and its implementation tech. Coroutine, Semaphore, event-driven programming, associative array Named parameter (keyword argument) (Ada, Python, Smalltalk, Common Lisp) Name mangling (name decoration): _Z on C, C++ Filename mangling : Unix file names can contain colons or backslashes To allow a better choice of programming language Numeric computation : C, FORTRAN, Ada AI : LISP, Prolog Internet applications : Perl, Java, HTML, XML, Web Service(SOAP), PHP, ASP.net, Python

Why study programming languages? (3) To make it easier to learn a new language Web programming (JavaScript, PHP), Semantic web Python To make it easier to design a new language User interface design *** C, COBOL, SMALLTALK의 덧셈의 속도차이를 초래하는 언어개념 및 구현의 차이

Evolution of software architecture 1950s - Large expensive mainframe computers ran single programs (Batch processing) 1960s - Interactive programming (time-sharing) on mainframes 1970s - Development of Minicomputers and first microcomputers. Apple II. Early work on windows, icons, and PCs at XEROX PARC 1980s - Personal computer - Microprocessor, IBM PC and Apple Macintosh. Use of windows, icons and mouse 1990s - Client-server computing - Networking, The Internet, the World Wide Web 2000s - P2P, Grid Computing, Web Service, Event-driven approach, Service-oriented programming, Script language, Cloud Computing …

Attributes of a good language (1) Clarity, simplicity, and unity - provides both a framework for thinking about algorithms and a means of expressing those algorithms Conceptual integrity 나쁜 예: APL, SNOBOL4 Orthogonality - every combination of features is meaningful Fewer exceptions  C언어에서 !!! Logical errors and inefficiency

Attributes of a good language(2) Naturalness for the application - program structure reflects the logical structure of algorithm Sequential algorithm, concurrent algorithm, logic algorithm, non-deterministic algorithm Appropriate data structures, operations, control structures, natural syntax Support for abstraction - program data reflects problem being solved Data abstraction <D,O,C> Encapsulation

Attributes of a good language (3) Ease of program verification - verifying that program correctly performs its required function Verification/validation standard, or specification requirements the needs of the intended end-user or customer Comments, assert() Design specification Programming environment - external support for the language Debugger, syntax-directed editor Supporting function, platforms Smalltalk Supporting all the software lifecycle phases

Attributes of a good language (continued) Portability of programs - transportability of the resulting programs from the computer on which they are developed to other computer systems Transportability C, C++, Pascal  Java (Byte-code) ML : single source implementation Cost of use - program execution, program translation, program creation, and program maintenance Code optimization, (Smalltalk, Perl), lifecycle costs

Language paradigms Imperative languages Goal is to understand a machine state (set of memory locations, each containing a value) Statement oriented languages that change machine state (C, Pascal, FORTRAN, COBOL, C++, Java) Syntax: S1, S2, S3, ... Applicative (functional) languages Goal is to understand the function that produces the answer Function composition is major operation (ML, LISP) Syntax: P1(P2(P3(X))) Programming consists of building the function that computes the answer

example1.f Nonexecutable Changing to REAL Sequential (by default) * A tiny program to plot my running times using GrADS * **************************************************************** * PARAMETER(NDAYS=365, UNDEF=-9.99, EMPTY=0.00) C REAL MIN(NDAYS) DIMENSION SEC(NDAYS) CHARACTER*27 HEADER CHARACTER*3 DAY CHARACTER*28 PATH PATH='/data/temp4/alfredo/fortran/' OPEN(1,FILE=PATH//'runtimes.data',FORM='FORMATTED', - STATUS=‘OLD') Changing to REAL Nonexecutable Sequential (by default)

example1.f Undefined value No value WRITE(*,2) HEADER READ (1,2) HEADER WRITE(*,2) HEADER WRITE(*,2) '----------------------------' C ND = 0 1 CONTINUE ND = ND+1 READ (1,3,END=4) DAY,DATE,MIN(ND),SEC(ND) WRITE(*,3) DAY,DATE,MIN(ND),SEC(ND) IF((MIN(ND).EQ.EMPTY).AND.(SEC(ND).EQ.EMPTY)) GO TO 4 GO TO 1 4 CONTINUE ND = ND - 1 !Taking away the last line because is blank CLOSE(1) 3 FORMAT(A3,2X,I8,2X,F5.2,2X,F5.2) WRITE(*,*)'-------------------------------------------' WRITE(*,*)'I AM RUNNING SINCE JULY 1, 2002!!!!!' WRITE(*,*)'THAT IS',ND,' DAYS AGO' runtimes.data DAY DATE MIN SEC MON 01072002 -9.99 -9.99 TUE 02072002 -9.99 -9.99 WED 03072002 19.00 43.00 THU 04072002 19.00 33.00 FRI 05072002 19.00 33.00 SAT 06072002 19.00 27.00 SUN 07072002 -9.99 -9.99 MON 08072002 19.00 46.00 . . . TUE 15102002 29.00 7.00 WED 16102002 -9.99 -9.99 THU 17102002 FRI 18102002 SAT 19102002 SUN 20102002 MON 21102002 TUE 22102002 WED 23102002 THU 24102002 FRI 25102002 SAT 26102002 SUN 27102002 No value

example1.f OPEN(2,FILE=PATH//'runtimes_gr.data',ACCESS='DIRECT', - STATUS='UNKNOWN',FORM='UNFORMATTED',RECL=1) C NDNOR = 0 NDSIR = 0 DO N = 1, ND IF((MIN(N).EQ.UNDEF).OR.(SEC(N).EQ.UNDEF)) THEN TIME = UNDEF NDNOR = NDNOR + 1 ELSE TIME = MIN(N)+SEC(N)/60. NDSIR = NDSIR + 1 ENDIF WRITE(2,REC=N) TIME ENDDO

example1.f WRITE(2,REC=ND+1) UNDEF !Just adding 1 and 2 extra WRITE(2,REC=ND+2) UNDEF !blank lines for plotting purposes CLOSE(2) WRITE(*,*)'WELL,',NDSIR,' DAYS LEAVING FOR A RUN' WRITE(*,*)'AND',NDNOR,' DAYS JUST BEING LAZY' WRITE(*,*)'-------------------------------------------' WRITE(*,*)'make ',ND+2,' days in the script file:' WRITE(*,*)'grads -blc "run runtimes.gs"' C 2 FORMAT(A27) C f77 example1.f C ./a.out END

COBOL II 000010 IDENTIFICATION DIVISION. 000020 PROGRAM-ID. SAMPLE. 000030 AUTHOR. J.P.E. HODGSON. 000040 DATE-WRITTEN. 4 February 2000 000041 000042* A sample program just to show the form. 000043* The program copies its input to the output, 000044* and counts the number of records. 000045* At the end this number is printed. 000046 000050 ENVIRONMENT DIVISION. 000060 INPUT-OUTPUT SECTION. 000070 FILE-CONTROL. 000080 SELECT STUDENT-FILE ASSIGN TO SYSIN 000090 ORGANIZATION IS LINE SEQUENTIAL. 000100 SELECT PRINT-FILE ASSIGN TO SYSOUT 000110 ORGANIZATION IS LINE SEQUENTIAL.

COBOL II 000120 000130 DATA DIVISION. 000140 FILE SECTION. 000150 FD STUDENT-FILE 000160 RECORD CONTAINS 43 CHARACTERS 000170 DATA RECORD IS STUDENT-IN. 000180 01 STUDENT-IN PIC X(43). 000190 000200 FD PRINT-FILE 000210 RECORD CONTAINS 80 CHARACTERS 000220 DATA RECORD IS PRINT-LINE. 000230 01 PRINT-LINE PIC X(80). 000240 000250 WORKING-STORAGE SECTION. 000260 01 DATA-REMAINS-SWITCH PIC X(2) VALUE SPACES. 000261 01 RECORDS-WRITTEN PIC 99. 000270

COBOL III 000270 000280 01 DETAIL-LINE. 000290 05 FILLER PIC X(7) VALUE SPACES. 000300 05 RECORD-IMAGE PIC X(43). 000310 05 FILLER PIC X(30) VALUE SPACES. 000311 000312 01 SUMMARY-LINE. 000313 05 FILLER PIC X(7) VALUE SPACES. 000314 05 TOTAL-READ PIC 99. 000315 05 FILLER PIC X VALUE SPACE. 000316 05 FILLER PIC X(17) VALUE 'Records were read'. 000318 05 FILLER PIC X(53) VALUE SPACES. 000319

COBOL IV 000320 PROCEDURE DIVISION. 000330 PREPARE-SENIOR-REPORT. 000340 OPEN INPUT STUDENT-FILE. 000350 OUTPUT PRINT-FILE. 000351 MOVE ZERO TO RECORDS-WRITTEN. 000360 READ STUDENT-FILE 000370 AT END MOVE 'NO' TO DATA-REMAINS-SWITCH. 000380 END-READ.

Language paradigms (continued) Rule-based languages Specify rule that specifies problem solution (Prolog, BNF Parsing) Other examples: Decision procedures, Grammar rules (BNF) Syntax: Answer  specification rule Programming consists of specifying the attributes of the answer Object-oriented languages Imperative languages that merge applicative design with imperative statements (Java, C++, Smalltalk) Syntax: Set of objects (classes) containing data (imperative concepts) and methods (applicative concepts)

New Paradigm Internet, Home Computing, Ubiquitous Computing, Embedded Computing, etc Languages and Compilers that are smart, small and safe Moveable code  agents Independent from machines and programming environments Supporting pragmatics or intelligence Java, XML, Mobile computing. Mobile code Event driven approach, Service-oriented Architecture, Web Service Supports multiple paradigms : Python 다양한 플래트폼, 응용시스템과 환경을 결합하여 사용자에 최적화한 느낌과 경험을 제공하는 통합된 응용시스템을 개발하는 환경

다음을 조사하라!! (1) Orthogonality가 C언어에서 발생시킬 수 있는 오류의 예를 들어라! (2)우리가 사용하는 언어는 왜 프로그래밍 언어로 부적합한가? (3) 스마트폰이 일반화하면서 ‘Platform’이란 말이 일반화하고 있다. ‘Platform’이란 무엇이며, 일반 응용프로그램과 어떤 차이가 나는가? 현재 널리 쓰이는 smartphone platform을 조사하고, 이 platform을 만드는 데 사용한 프로그래밍언어와 응용소프트웨어(앱)과 연결 가능한 언어 및 연결 방법을 조사하라.