Chapter 1

Question 1

1. Why is it useful for a programmer to have some background in language design, even
   though he or she may never actually design a programming language?

Answer 1

• Increased Capacity to express Ideas
• Improved background for choosing appropriate languages
• Increased ability to learn new languages
• Better understanding of the significance of Implementation
• Better use of languages that are already Known
• Overall advancement of computing

Question 2

2. How can knowledge of programming language characteristics benefit the whole
   computing community?

Answer 2

If those who choose languages are better informed, better languages would eventually squeeze out poorer ones.

Question 3

3. What programming language has dominated scientific computing over the past 50
   years?

Answer 3

FORTRAN (short for FORmula TRANslation).

Question 4

4. What programming language has dominated business applications over the past 50
   years?

Answer 4

COBOL (short for COmmon Business Oriented Language).

Question 5

5. What programming language has dominated artificial intelligence over the past 50
   years?

Answer 5

LISP (short for LISt Processor).

Question 6

6. In what language is most of UNIX written?

Answer 6

C

Question 7

7. What are the disadvantages of having too many features in a language?

Answer 7

It reduces readability because features like feature multiplicity and operator overloading create different “subsets” of the language, making code hard for others to understand.

Question 8

8. How can user-defined operator overloading harm the readability of a program?

Answer 8

Operator overloading harms readability because it allows standard symbols to perform unexpected operations, confusing the reader.

Question 9

9. What is one example of a lack of orthogonality in the design of C?

Answer 9

You can return a structure (record) from a function, but you cannot return an array.

Question 10

10. What language used orthogonality as a primary design criterion?

Answer 10

ALGOL 68

Question 11

11. What primitive control statement is used to build more complicated control statements
    in languages that lack them?

Answer 11

The goto statement

Question 12

12. What construct of a programming language provides process abstraction?

Answer 12

Subprograms

Question 13

13. What does it mean for a program to be reliable?

Answer 13

A program is reliable if it performs to its specifications and handles errors gracefully under all conditions.

Question 14

14. Why is type checking the parameters of a subprogram important?

Answer 14

Type checking the parameters is important because it ensures reliability by detecting errors where a function receives incompatible data. (e.g., receiving an integer bit-string when it expects a float)

Question 15

15. What is aliasing?

Answer 15

Having two or more distinct names that can be used to access the same memory cell.

Question 16

16. What is exception handling?

Answer 16

The ability of a program to intercept run-time errors, take corrective measures, and then continue execution.

Question 17

17. Why is readability important to writability?

Answer 17

Because writing a program involves frequently re-reading the parts you have already written. If you can’t read it easily, you can’t write/modify it efficiently.

Question 18

18. How is the cost of compilers for a given language related to the design of that language?

Answer 18

If the language design is very complex (like early Ada), the compilers are expensive to build and run. If the design is simple, compilers are cheaper.

Question 19

19. What have been the strongest influences on programming language design over the past 50 years?

Answer 19

Computer architecture (Von Neumann) and programming design methodologies.

Question 20

20. What is the name of the category of programming languages whose structure is dictated by the von Neumann computer architecture?

Answer 20

Imperative languages.

Question 21

21. What two programming language deficiencies were discovered as a result of the research in software development in the 1970s?

Answer 21

Incompleteness of type checking and inadequacy of control statements.

Question 22

22. What are the three fundamental features of an object-oriented programming language?

Answer 22

Data abstraction, inheritance, and dynamic (run-time) method binding.

Question 23

23. What language was the first to support the three fundamental features of object-oriented programming?

Answer 23

Smalltalk

Question 24

24. What is an example of two language design criteria that are in direct conflict with each other?

Answer 24

Reliability vs. Cost of Execution (e.g., Java’s array index checking makes it safer but slower).

Also, Writability vs. Readability (e.g., APL is very concise/writable but hard to read).

Question 25

25. What are the three general methods of implementing a programming language?

Answer 25

Compilation, pure interpretation, and hybrid implementation systems.

Question 26

26. Which produces faster program execution, a compiler or a pure interpreter?

Answer 26

A compiler

Question 27

27. What role does the symbol table play in a compiler?

Answer 27

It serves as a database for the compilation process, storing type and attribute information for every user-defined name.

Question 28

28. What does a linker do?

Answer 28

It collects system programs and libraries and links them to the user program, creating an executable image (load module)

Question 29

29. Why is the von Neumann bottleneck important?

Answer 29

It is the primary limiting factor in the speed of computers.

Question 30

30. What are the advantages in implementing a language with a pure interpreter?

Answer 30

Pure interpretation allows for easy implementation of source-level debugging operations (error messages can refer to specific lines in the source code).

Question 31

What is expressivity

Answer 31

Expressivity is how concisely a language can specify computations to reduce code bulk.

Question 32

What is writability

Answer 32

A measure of how easily a language can be used to create programs.

Question 33

What is type checking

Answer 33

Type checking is simply testing for type errors in a given program, either by the compiler or during program execution.

Question 34

What are the two types of abstraction

Answer 34

1. Process abstraction 2. Data abstraction

Question 35

What are the two syntax consideration in syntax design?

Answer 35

1. Special words (for example, while, class, and for) 2. Form and Meaning (designing statements so their form can indicate its purpose)

Question 36

What affects Readability?

Answer 36

1. Overall simplicity - Feature multiplicity - Operator overloading 2. Orthogonality 3. Data types 4. Syntax design

Question 37

What affects Writability?

Answer 37

1. Simplicity and orthogonality 2. Support for abstraction 3. Expressivity

Question 38

What affects Reliability?

Answer 38

1. Type checking 2. Exception Handling 3. Aliasing 4. Readability and Writability

Question 39

List the programming domains

Answer 39

1. Scientific applications 2. Business applications 3. Artificial intelligence 4. Systems programming 5. Web Software