CSci 1301: Problem Set 4

Due: Friday, October 10 in class or by email before the class time 10:30am

Problem 1: Written exercises

Written exercises can be submitted electronically or on paper, in one of the following ways:

on paper in class on the due date or in my office (slide it under the door if I am not there) at any point before the deadline,
in an email message with the rest of your problem set,
as an attachement to an email message with the rest of your problem set,
as a google doc shared with me. Please give me permissions to re-share so that I can share it with the TA, and do not make any changes after the submission deadline.

Book exercises for this part are given in the section Intermezzo: BSL

(3 points) Exercises 108 (question 3 only), 109 (questions 2,3)
(5 points) For each of the following expressions and definitions indicate if they are legal or illegal. Explain your answers (otherwise you may not get credit even for a correct answer)
```
(define cond 4)

(cond [true 1 false 0])

(define (f x)
  (+ x (f x)))

(define (g "input")
  (+ (string-length "input") 1))

(define (h InPuT)
  (+ (string-length InPuT) 1))
```
(4 points) Exercise 112 (questions 2,3 only)
(8 points) Exercise 113, 115, 117 questions 1,2 (note: evaluation of some expressions may lead to an error)

Problem 2: Traffic light (12 points)

Exercise 99 in Section 6.2. Start designing your solution by deciding on what your world state will be. Make sure to describe your world state in comments right before main. Include check-with in your big-bang to check that your world state is in a valid state, it is a requied part of this problem.

CSci 1301 course web site.