CIS 352   —   SPRING 2008

Exam 3: Scope and Practice

Version 1 — April 18

When, Where, and How

• When: Thursday, April 29
• Where: in class
• How: Closed book, closed notes.

Coverage

• Dybvig through chapter 2.
• EOPL Chapters 1, 2, 3, and 7.

Topics

• You should be familiar with all the topics from Exam 1 and Exam 2.

• Terms.

  Know the following terms, all of which are in the index of the text or in notes I've provided. Be able to define them and apply them (or give an example). For example, be able to define what a bound variable is and to pick out the bound variables in some Scheme code. The terms that are new from last time are in red and underlined below.

  • abstract syntax
  • actual parameter
  • alpha-conversion
  • applicative-order reduction
  • BNF
  • beta conversion
  • beta redex
  • bound variable
  • call-by-name parameter passing
  • call-by-need parameter passing
  • call-by-reference parameter passing
  • call-by-value parameter passing
  • call-by-value-result
  • capture of a variable
  • concrete syntax
  • control context
  • continuation
  • contours
  • defined language
  • defining language
  • direct target
  • dynamic scoping
  • environment
  • expressed value
  • formal parameter
  • higher-order procedure
  • hole in a scope
  • indirect target
  • lambda calculus
  • lazy evaluation
  • lexical address
  • normal form
  • normal-order reduction
  • nested region
  • occurs bound
  • occurs free
  • substitution
  • syntactic category
  • thunk
  • variable aliasing
  • variable assignment

• Be prepared for the following sorts of questions.

  ---

  • What does the following code return when

    1. call-by-value parameter passing is used?
    2. call-by-reference parameter passing is used?
    3. call-by-name parameter passing is used?
    4. call-by-need parameter passing is used?
    5. call-by-value-result parameter passing is used?
    Explain your answers.

    ---

  • What does the following code return when

    1. lexical scoping is used in the language?
    2. dynamic scoping is used in the language?
    Explain your answers.

    ---

  • Here's an expression in our defined language involving the try-handle construct: what is the value of the expression?

    ---

  • Write a Scheme procedure to do X
    (where X is something not too involved).

    ---

  • Extend our basic interpreter to handle Y
    (where Y is something not too involved).

    ---

  • Extend our continuation-passing interpreter to handle Z
    (where Z is something not too involved).

• Last year's Exam 3 with sample solutions.

   For part (a) the answers should be: 120 for lexical scoping   and   480 for dynamic scoping
   For part (b) the answers should be: 1024 for lexical scoping   and   20180 for dynamic scoping