Chapter 1

Question 1

Why should Concepts of programming languages be studied?

Answer 1

Programming is new.
General language concept knowledge helps.
Increased ability to express ideas.
“ “ to learn new languages.
Helps choose appropriate languages.
Understand tradeoffs.
Overall advancement of computing

Question 2

What are the Language Evaluation Criteria?

Answer 2

Readability, Writability, Reliability, Cost

Question 3

What is Readability defined as?

Answer 3

The ease with which programs can be read and understood

Question 4

What is Writability defined as?

Answer 4

The ease with which a language can be used to create programs

Question 5

What is Reliability defined as?

Answer 5

Whether a language performs to its specifications under all conditions

Question 6

What is Cost defined as?

Answer 6

cost of using the language

Question 7

What is the Evaluation Criteria for Readability?

Answer 7

Overall simplicity: Manageable set of features and constructs(minimal feature multiplicity, minimal operator overloading)

Orthogonality: small set of primitive constructs can be combined in small number of ways

Data types; if types are missing, they must be simulated

Syntax considerations: Lack of naming restrictions increase readability (Identifier forms). More special words = more readable (Special words). meaningful keywords, avoid language constructs with same name and different meaning(Form and meaning)

Question 8

Why is a lack of orthogonality bad?

Answer 8

It can lead to exceptions

Question 9

Why is too much orthogonality bad?

Answer 9

bad for readability

Question 10

What is the problem with too much simplicity?

Answer 10

Can be bad for readability

Question 11

What is the Evaluation Criteria for Writability?

Answer 11

Simplicity and orthogonality: few constructs, small number of primitives, small set of rules for combining them

Support for abstraction: define and use complex structures/operations.(Process abstraction and Data abstraction)

Expressivity: convenient ways of specifying operations. Strength + number of operators and predefined functions

Question 12

What is process abstraction?

Answer 12

Provision for subprograms

Question 13

What is data abstraction?

Answer 13

classes, pointer & dynamic memory

Question 14

What is the Evaluation Criteria for Reliability?

Answer 14

Type checking: Test for type errors. Compile time checking > run time checking

Exception handling: intercept run time errors and correct it

Aliasing: Presence of 2+ distinct referencing names for same memory location. (dangerous feature)

Readability and writability: non-natural ways of expressing algorithms = unnatural approaches = reduced reliability

Question 15

What is the Evaluation Criteria for Cost?

Answer 15

Training new programmers.
Writing programs
compiling programs
Executing programs
Language implementation system (availability of free compilers)
Reliability(poor = high cost)
Maintaining programs

Question 16

What are some extra Evaluation Criteria?

Answer 16

Portability : ease of moving from on implementation to another
Generality: applicability to a wide range of applications
Well-definedness: Completeness + precision of of language’s official definition

Question 17

What are the Language Design trade-offs

Answer 17

Reliability vs cost of execution

Readability vs writability

Writability(flexibility) vs reliability

Question 18

What are the programming domains?

Answer 18

Scientific Applications
Business Applications
AI
System Programming
Web Software

Question 19

What influences the Design of a Language?

Answer 19

Computer Architecture
Programming Methodologies (eg OOP led to new programming paradigms)

Question 20

What influenced Programming Methodologies?

Answer 20

1950/60: simple applications (machine efficiency)
1960s: Efficiency + readability + better control structures (structured programming + top-down design + step-wise refinement)
1970: Process- oriented -> data-oriented (data abstraction
1980: OOP (Abstraction + inheritance + polymorphism)

Question 21

What are the Language Categories?

Answer 21

Imperative: Variables, assignment statements, iteration. has OOP languages. Includes visual languages. (c++ Java C ..)

Functional : Main means of computation, applying functions to parameters (LIST, Scheme)

Logic: Rule based (Prolog)

Markup/hybrid (XSLT, JSTL)

Question 22

What are the Implementation Methods

Answer 22

Compilation: programs translated to ML

Pure Interpretation: Programs are interpreted by another program known as an interpreter

Hybrid: compromise between compilers and pure interpreters

Question 23

What are the phases of Compilation

Answer 23

Lexical analysis: converts source characters to lexical units

Syntax Analysis: Transforms lexical units to parse trees

Semantics analysis: Generate intermediate code

Code generation: Machine code is generated

Question 24

Is Compiled or Pure Interpreted programs faster

Answer 24

Compiled.
Interpreted programs are 10-100 times slower

Question 25

Does Interpreted or compiled programs use more space

Answer 25

Interpreted.

Question 26

What is an example of a Hybrid Implementation System

Answer 26

Perl, typical Java programs

Question 27

What is Just-In-Time Implementation Systems

Answer 27

Translate programs to intermediate language
Compile the intermediate language into machine code when they are called

Question 28

What uses JIT systems?

Answer 28

.NET languages

Question 29

What are the different Programming environments?

Answer 29

UNIX, Microsoft Visual Studio.NET,NetBeans