Q&A Assignment #4 Problem Set

Name : Vina Melinda
NIM : 1801380106

Untuk kali ini saya akan menjawab Assignment #4 Problem Set dari Chapter 2 dari Sebesta.

Q&A Sessions:

6. Q: Make an educated guess as to the most common syntax error in LISP programs.
A: Undefined escape sequences in literal strings. The backslash character can be used in literal strings and characters :
       - to escape various characters
       - to introduce an escape sequence representing a character

7. Q: LISP began as a pure functional language but gradually acquired more and more imperative features. Why?
A: John McCarthy’s original interest in developing LISP was to meet the demand for artificial intelligence as a functional programming language, but there soon emerged different dialects, cleaners, more modern, and more imperative, that began to deviate from the functional form into Scheme. COMMON LISP combined the different forms into a single form that was more imperative, including assignment and iteration.

8. Q: Describe in detail the three most important reasons, in your opinion, why ALGOL 60 did not become a very widely used language.
A: Excessive flexibility hurt ALGOL60 since languages that are difficult to learn were not as well received as languages with a more rigid structure. Allowing a large number of possibilities also introduces an element of inefficiency since the methods to complete a task would differ between programmers.

Second, notes that its association with BNF alienated the language as strange and complicated. If programmers are not excited about using a language, they will always find a different one.

The third and perhaps the most important reason that ALGOL 60 was not very widely used was because of a lack of support from IBM, who was at the time the preeminent company for using computer languages. Without some help from a large corporation, ALGOL 60 did not have much of a chance, much like COBOL without the DoD

9. Q: Why, in your opinion, did COBOL allow long identifiers when Fortran and ALGOL did not?
A: COBOL required that managers without a background in programming should be able to read programs. This caused identifiers to be longer, making the language more English-like.

10. Q: Outline the major motivation of IBM in developing PL/I.
A: Like Fortran, PL/I was developed as an IBM product. By the early 1960s, the users of computers in industry had settled into two separate and quite different camps: scientific and business. From the IBM point of view, scientific programmers could use either the large-scale 7090 or the small-scale 1620 IBM computers. This group used floating-point data and arrays extensively

For business applications, people used the large 7080 or the small 1401 IBM computers. They needed the decimal and character string data types, as well as elaborate and efficient input and output facilities. They used COBOL, although in early 1963 when the PL/I story begins

The two widely separated computer user groups were moving toward each other in ways that were thought certain to create problems This perceptions naturally led to the concept of designing a single universal computer that would be capable of doing both floating-point and decimal arithmetic, and therefore both scientific and business applications.