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Introduction

Programming Language Design and Implementation (4th Edition)by T. Pratt and M. Zelkowitz

Prentice Hall, 2001

Sections 1-1.3.2

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Organization of Programming Languages

• Understand how languages are designed and implemented

• Syntax -- What a program looks like• Semantics -- What a program means• Implementation -- How a program executes

• Understand most appropriate language for solving specific problems, For example:

• Pascal, C -- procedural, statement oriented• C++, Java, Smalltalk -- Object oriented• ML, Lisp -- Functional • Prolog -- Rule-based

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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 desi

gn concepts - encapsulation, records, inheritance, functionality, assertions

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Era Application Majorlanguages

Otherlanguages

Business COBOL AssemblerScientific FORTRAN Algol, BASIC,

APLSystem Assembler JOVIAL, Forth

1960s

Artificialintelligence

LISP SNOBOL

Business COBOL, C++,Java, spreadsheet

C, PL/I, 4GLs

Scientific FORTRAN, C,C++, Java

BASIC

System C, C++, Java Ada, BASIC,Modula

Artificialintelligence

LISP, Prolog

Publishing TeX, Postscript,word processing

Process UNIX shell, TCL,Perl, Javascript

AWK, Marvel,SED

Today

New paradigms ML, Smalltalk Eiffel

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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

Malloc() garbage collection

Implementation details of recursion, object classes, subroutine calls, …

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Why study programming languages? (2)

• To increase your vocabulary of useful programming constructs

Increase programming vocabulary and its implementation tech.

Coroutine • To allow a better choice of programming language

Numeric computation : C, FORTRAN, Ada

AI : LISP, Prolog

Internet applications : Perl, Java

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Why study programming languages? (3)

• To make it easier to learn a new language• To make it easier to design a new language

User interface design

• *** C, COBOL, SMALLTALK 의 덧셈의 속도차이

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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

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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

APL

SNOBOL4• Orthogonality -every combination of features is mean

ingful

Fewer exceptions

Logical errors and inefficiency

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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

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Attributes of a good language (3)

• Ease of program verification - verifying that program correctly performs its required function Verification/validationComments, assert()Design specification

• Programming environment - external support for the languageDebugger, syntax-directed editorSupporting function, platformsSmalltalk Supporting all the software lifecycle phases

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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

ML : single source implementation• Cost of use - program execution, program translatio

n, program creation, and program maintenance

Code optimization, (Smalltalk, Perl), lifecycle costs

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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 sta

te (C, Pascal, FORTRAN, COBOL)• 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 c

omputes the answer

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Language paradigms (continued)

• Rule-based languages• Specify rule that specifies problem solution (Prolo

g, 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 w

ith imperative statements (Java, C++, Smalltalk)• Syntax: Set of objects (classes) containing data (im

perative concepts) and methods (applicative concepts)

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