CS 250 - Programming Languages
Spring 2001

Read chapters 3 and 4 of the book, and answer the following questions. I need hard-copy of everything, and electronic copy of your program(s).

1. Answer question 3-7 in your book (you may use Java if you wish, but please specify what language you used).
2. Answer question 4-7 in your book.
3. Answer question 4-8 in your book.
4. Design a recursive descent parser for the syntactic class Statements in language Jay, using the Abstract and Concrete Syntax of Jay in Appendix B of your book and your TokenStream class from Assignment 2 as a basis.  The output of this parser should be an abstact syntax tree for an instance of Statements (You may work in teams of two on this question).  A skeleton version of the parser and a simple driver program are available in the directory ~echown/courses/250/interpreter.  Copy the files ConcreteSyntax0.java, Program0.java, and Interpreter0.java to your working directory before starting this program. 
5. Is Jay a statically typed or dynamically typed language?  Explain.
6. Extra credit: Add a display method to the appropriate abstract syntax classes so that an abstract syntax tree for Assignment can be displayed in indented notation.  That is, the Assignment z = 2*x + 3/y - 4; should be displayed by your methods as follows when its abstract representation is passed to the display method:

Assignment:
    Target: Variable: z
    Source: Binary:
        Operator: -
        Binary:
            Operator: +
            Binary:
                Operator: *
                Value: 2
                Variable: x
            Binary:
                Operator: /
                Value: 3
                Variable: y
        Value: 4
Note that the indented notation represents a tree in which the root of each subtree is at one tab position and the descendents are indented one tab position to the right of that root on subsequent lines.