1. School of Computer & Information Engineering,
Chapter 1 :: Introduction
Origin : Michael L. Scott
School of Computer & Information Engineering,
Sangji University
Kwangman Ko

2. Reading 1, P40.
Reading 2, P40

3. 1. Introduction, P41 Why are there so many programming languages?
evolution - we've learned better ways of doing things over time
socio-economic factors: proprietary interests, commercial advantage
orientation toward special purposes
orientation toward special hardware
diverse ideas about what is pleasant to use

4. Introduction What makes a language successful? , PP42-43.
easy to learn(BASIC, Pascal, LOGO, Scheme)
easy to express things, easy use once fluent, "powerful”
C, Common Lisp, APL, Algol-68, Perl, …
easy to implement (BASIC, Forth)
possible to compile to very good (fast/small) code (Fortran)
backing of a powerful sponsor (COBOL, PL/1, Ada, Visual Basic)
wide dissemination at minimal cost (Pascal, Turing, Java)

5. 1.2 Program Language Spectrum, PP45-46.
Classified into families based on Model of Computation
Declarative Programming Language
focused on WHAT the computer is to do.
More higher level, tune with the programmer’s point of view.
Imperative Programming Language
focused on HOW the computer should do it.
dominate, mainly for performance reasons

6. Declarative programming language
Functional
Scheme, ML, pure Lisp, FP, …
logic, constraint-based:
Prolog, VisiCalc, RPG, …
Imperative programming language
von Neumann:
Fortran, Pascal, Basic, C, …
object-oriented:
Smalltalk, Eiffel, C++, …
scripting languages:
Perl, Python, JavaScript, PHP, …

7. 1.3 Why study programming languages?, P47~
Help you choose a language.
for systems programming
C vs. Modula-3 vs. C++
for numerical computations
Fortran vs. APL vs. Ada
for embedded systems
Ada vs. Modula-2
for symbolic data manipulation
Common Lisp vs. Scheme vs. ML
for networked PC programs
Java vs. C/CORBA

8. Reading, P48. Understand OBSCURE features:
Choose among alternative ways to express things
understand implementation costs
Make good use of debuggers, assemblers, linkers, and related tools
Simulate useful features in languages that lack them

9. 1.4 Compilation vs. Interpretation
not opposites
not a clear-cut distinction
Input Data
Compiler
Target Program
Source Program
Outputs
Source Program
Interpreter
Outputs
Input Data

10. Compilation vs. Interpretation
Pure Compilation
translates the high-level source program into an equivalent target program(typically in machine language).
COMPILER 원시
프로그램
Frontend
중간코드
Backend 목적
프로그램

11. Pure Interpretation Reading, P51.
stays around for the execution of the program
the locus of control during execution
Reading, P51.
Interpretation
Greater flexibility
Better diagnostics (error messages)
Compilation
Better performance

12. Most language implementations, ☞ P 51.
a mixture of both compilation and interpretation
compilation or simple pre-processing, followed by interpretation
source program
translator
intermediate program
Virtual Machine
(interpreter)
Input Data
Output

13. translator Virtual Machine (interpreter) Java compiler
source program
translator
intermediate program
Virtual Machine
(interpreter)
Input Data
Output
Test.java
Java compiler
(javac Test.java )
Test.class
Java interpreter
(java Test.class)

14. Preprocessor Removes comments and white space
Groups characters into tokens (keywords, identifiers, numbers, symbols)
Expands abbreviations in the style of a macro assembler
Identifies higher-level syntactic structures (loops, subroutines)

15. Library of Routines and Linking
Reading, P52.
Compiler uses a linker program to merge the appropriate library of subroutines (e.g., math functions such as sin, cos, log, etc.) into the final program:
source program
compiler
Incomplete
machine program
Library Routines
LINKER
machine program

16. Post-compilation Assembly
Facilitates debugging (assembly language easier for people to read)
Isolates the compiler from changes in the format of machine language files (only assembler must be changed, is shared by many compilers)

17. The C Preprocessor (conditional compilation)
Preprocessor deletes portions of code, which allows several versions of a program to be built from the same source

18. Source-to-Source Translation (C++)
C++ implementations based on the early AT&T compiler generated an intermediate program in C, instead of an assembly language:

19. Bootstrapping

20. Dynamic and Just-in-Time(JIT) Compilation
Reading, P56.
In some cases a programming system may deliberately delay compilation until the last possible moment.
The Java language definition defines a machine-independent intermediate form known as byte code. Byte code is the standard format for distribution of Java programs.
The main C# compiler produces .NET Common Intermediate Language (CIL), which is then translated into machine code immediately prior to execution.

21. Compilation vs. Interpretation
Tools

22. 1.5 Programming Environments

23. 1.6 An Overview of Compilation, PP59-60.