CS 380: Lisp Assignment Solutions and Exercises, Assignments of Computer Science

Download CS 380: Lisp Assignment Solutions and Exercises and more Assignments Computer Science in PDF only on Docsity! CS 380: Optional Lisp Assignment Fall 2007 1. Describe what happens when the following expressions are evaluated: (a) (+ (- 5 1) (+ 3 7)) (b) (list 1 (+ 2 3)) (c) (if (listp 1) (+ 1 2) (+ 3 4)) (d) (list (and (listp 3) t) (+ 1 2)) 2. Give three distinct cons expressions that return (a b c). 3. Using car and cdr, define a function to return the fourth element of a list. 4. Define a function that takes two arguments and returns the greater of the two. 5. What do the following functions do? (a) (defun enigma(x) (and (not (null x)) (or (null (car x)) (enigma (cdr x))))) (b) (defun mystery (x y) (if (null y) nil (if (eql (car y) x) 0 (let ((z (mystery x (cdr y)))) (and z (+ z 1)))))) 6. Show the following lists in box notation: (a) (a b (c d)) (b) (a (b (c (d)))) (c) (((a b) c) d) (d) (a (b . c) . d) 7. Write a version of union that preserves the order of the elements in the original lists. For example: [1]> (new-union ’(a b c) ’(b a d)) (A B C D) 8. Write a recursive function that takes an integer as input and returns the “reverse” of that integer. The function should not need to call any supplementary functions (i.e., those that are not built into common lisp). Your function may use conversion to strings/lists, although it must return an integer. There is a way of doing this without using strings (Hint: think logarithms, exponentiation, and modulus). Here’s an example of like what the output should look: [1]> (reverse-integer 12345) 54321 Many of these problems were adapted from ANSI Common Lisp by Paul Graham (ISBN 0-13-370875-6): the book that used to be required for this class. 1