Summer  2008                                Final Examination                                     Prasad

1.   Recursive Definition in Scheme (7 + 6  pts)

Consider the list functions computed by the following Standard (R5RS) Scheme definitions. 

   (define (mystery   lis)
            (if (null? lis) lis
                [if (symbol? (car lis)) (mystery (cdr lis))                                       '()
                ]               
            )
     )

   (define (mysteryDeepens f id lis)
            (if (null? lis) id
                [f (car lis) (mysteryDeepens f id (cdr lis))]
            )
     )

What are the values of (mystery '(a b c d)), (mystery '(a b 1 2 c d)) and (mysteryDeepens + 200 '(1 2 3 4))?

Explain clearly the list functions computed by the above Scheme definitions. (Your explanation should be sufficiently precise. That is, write two questions for which these two definitions are the answers (a la Jeopardy).)

2.  Java Concepts (6 + 5 + 5 pts)

• Java does not permit overriding run()-method in a subclass of class java.lang.Thread to be declared private, or throw InterruptedException. Explain why?
• Explain what is meant by the term method binding? Illustrate the difference between static binding and dynamic binding? Be to the point.
• The inheritance of overloaded methods in Java and C++ differ in a fundamental way. Clearly show the difference in the two approaches taken and argue why Java's design decision is preferable.

3.  Recursive Definition (4 + (1 + 2 + 4) pts)

Study the Java program given on the reverse side carefully and answer the following questions.

• Specify the grammar for the input language in EBNF form. (Use a pair of curly braces for Kleene Star operation.)
• What is the result of invoking the program on the exprFinal.dat file containing the following 3 expressions.

        x
        x - y
        x - y - y