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# Lattay's solution

## to Bob in the Scheme Track

Published at Feb 19 2020 · 0 comments
Instructions
Test suite
Solution

#### Note:

This exercise has changed since this solution was written.

Bob is a lackadaisical teenager. In conversation, his responses are very limited.

He answers 'Whoa, chill out!' if you yell at him.

He says 'Fine. Be that way!' if you address him without actually saying anything.

He answers 'Whatever.' to anything else.

## Source

Inspired by the 'Deaf Grandma' exercise in Chris Pine's Learn to Program tutorial. http://pine.fm/LearnToProgram/?Chapter=06

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

### bob-test.scm

``````;; Load SRFI-64 lightweight testing specification
(use-modules (srfi srfi-64))

;; Suppress log file output. To write logs, comment out the following line:
(module-define! (resolve-module '(srfi srfi-64)) 'test-log-to-file #f)

;; Require bob impl
(use-modules (bob))

;;; Begin test suite
(test-begin "bob-test")

(test-equal "responds-to-something"
"Whatever."
(response-for "To-may-to, tom-aaaah-to."))

(test-equal "responds-to-shouts"
"Whoa, chill out!"
(response-for "WATCH OUT!"))

(test-equal "responds-to-questions"
"Sure."
(response-for "Does this cryogenic chamber make me look fat?"))

(test-equal "responds-to-forceful-talking"
"Whatever."
(response-for "Let's go make out behind the gym!"))

(test-equal "responds-to-acronyms"
"Whatever."
(response-for "It's OK if you don't want to go to the DMV."))

(test-equal "responds-to-forceful-questions"
"Whoa, chill out!"
(response-for "WHAT THE HELL WERE YOU THINKING?"))

(test-equal "responds-to-shouting-with-special-characters"
"Whoa, chill out!"
(response-for "ZOMG THE %^*@#\$(*^ ZOMBIES ARE COMING!!11!!1!"))

(test-equal "responds to shouting numbers"
"Whoa, chill out!"
(response-for "1, 2 ,3, GO!"))

(test-equal "responds-to-shouting-wit-no-exclamation-mark"
"Whoa, chill out!"
(response-for "I HATE YOU"))

(test-equal "responds-to-statement-containing-question-mark"
"Whatever."
(response-for "Ending with ? means a question."))

(test-equal "responds-to-silence"
"Fine. Be that way!"
(response-for ""))

(test-equal "responds-to-prolonged-silence"
"Fine. Be that way!"
(response-for "     "))

(test-equal "responds-to-only-numbers"
"Whatever."
(response-for "1, 2, 3"))

(test-equal "responds-to-number-question"
"Sure."
(response-for "4?"))

(test-end "bob-test")
;;; End test suite``````
``````(define-module (bob)
#:export (response-for))

(define (is-silence? str)
(let loop ((rest (string->list str)))
(if (null? rest)
#t
(if (eq? #\space (car rest))
(loop (cdr rest))
#f))))

(define (contain-letter? str)
(let loop ((rest (string->list str)))
(if (null? rest)
#f
(if (char-alphabetic? (car rest))
#t
(loop (cdr rest))))))

(define (is-shouting? str)
(and
(contain-letter? str)
(equal? str (string-upcase str))))

(define (end-with? char str)
(let loop ((rest (string->list str)) (last #f))
(if (null? rest)
last
(loop (cdr rest) (eq? #\? (car rest))))))

(define (is-question? str)
(end-with? #\? str))

(define (response-for question)
(cond
((is-silence? question)
"Fine. Be that way!")
((is-shouting? question)
"Whoa, chill out!")
((is-question? question)
"Sure.")
(else
"Whatever.")))``````