Computer Science 5641
Compiler Design
Homework Assignment 4 (20 points)
Due December 3, 2009

1. The grammar below defines lists of lists of literals. A list type can be declared as a "list of" type and a list literal is made as a set of expressions between parentheses separated by commas. Write syntax directed translation rules to type the expressions in this grammar and check that types match (e.g., a list must be of one type).
   • P → D ; E
   • D → D ; D | id : T
   • T → list ofT | char | integer
   • E → ( L ) | literal | num | id
   • L → E , L | E
2. Exercise 6.5.1, page 398
3. What is printed by the program below for (a) call by value, (b) calue by reference and (c) call by value-result. Assume that an argument that includes an operator has a temporary variable created to holds it value:

           void p (x, y, z) {
               print(x,y,z);
               y = y + 1;
               z = z + x;
               print(x,y,z);
           }
           print(a,b);
           a = 2;
           b = 3;
           p(a + b, a, a);
           print(a,b);
     

4. Languages that use dynamic scoping cannot be typed at compile time. Explain why with an example.