The Department of Computer Science & Engineering

CSE202: Programming in Lisp




Part I
  Chap 1
  Chap 2
  Chap 3
  Chap 4
  Chap 5
  Chap 6
  Chap 7
  Chap 8
  Chap 9
Part II
  Chap 10
  Chap 11
  Chap 12
  Chap 13
  Chap 14
  Chap 15
  Chap 16
  Chap 17
  Chap 18
  Chap 19
  Chap 20
  Chap 21
  Chap 22
  Chap 23
Part III
  Chap 24
  Chap 25
  Chap 26
  Chap 27
  Chap 28
  Chap 29
  Chap 30
  Chap 31
  Chap 32
Page 184, line -1: Change (setq x 3) to (setf x 3).

  1. Read Chapter 25.

  2. Do Exercises 25.1 - 25.3 to the extent you feel you need to in order to understand the material.

  3. Do Exercise 25.4. The text mentions that versions of Lisp older than Common Lisp were dynamically scoped (instead of lexically scoped, which Common Lisp is). The Lisp that was used to implement XEmacs (and other versions of Emacs), called Emacs Lisp or ELisp, is also dynamically scoped. You can see this by doing Exercise 25.4 in the *scratch* buffer. The *scratch* buffer is a top-level listener for Emacs Lisp, and is very similar to interacting with the top-level of ACL, but to evaluate a form you type a C-j. That will evaluate the immediately preceding form. Compare ACL's behavior to ELisp's behavior on this exercise.

  4. Do Exercises 25.5 - 25.8 carefully to learn more about global and local variables, and to learn about declarations.

  5. Create a file named with one function defined in the ch25 package. This should be a function named stack that takes one optional argument whose default value is the empty list. Let's say that lambda variable is named stk. The function stack should return a closure which is a function of one required argument called operation and one optional argument called element. The free variable of the closure should be the variable stk. The closure should operate as follows:
    • If operation is the symbol push, use setf to push the element onto stk, and return the value of stk.

    • If operation is the symbol pop, use setf to pop the top element off stk, and return the value of stk.

    • If operation is the symbol top, return the top element of stk.

    Here's an example of stack in operation:

    CH25(19): (setf s1 (stack))
    #<Interpreted Closure (:INTERNAL STACK) @ #x46b4742>
    CH25(20): (funcall s1 'push 'z)
    CH25(21): (funcall s1 'push 'y)
    (Y Z)
    CH25(22): (setf s2 (stack '(m)))
    #<Interpreted Closure (:INTERNAL STACK) @ #x46b4bba>
    CH25(23): (funcall s2 'push 'a)
    (A M)
    CH25(24): (funcall s2 'push 'b)
    (B A M)
    CH25(25): (funcall s1 'pop)
    CH25(26): (funcall s1 'top)
    CH25(27): (funcall s2 'top)
    Submit your


Copyright © 1999, 2000 by Stuart C. Shapiro. All rights reserved.

Stuart C. Shapiro <>