suzanne.soy/racket
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

typos

Browse Source
This commit is contained in:
Matthias Felleisen 2012-12-21 18:41:29 -05:00
parent 19d6f7a15a
commit ff701abe7b
1 changed files with 206 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

206
collects/realm/chapter2/source.rkt Normal file
View File

@ -0,0 +1,206 @@
#lang racket
(require rackunit rackunit/text-ui)
;; Play a Guess my Number game at the REPL.
;; Run program.
;; Pick a number X between <n> and <m>.
;; Evaluate
;; (start <n> <m>)
;; The program will respond with a number.
;; Use
;; (bigger)
;; and
;; (smaller)
;; to let it know what you think of the guess.
;; Watch how qiuckly the program guesses X.
;
;
;
; ;
; ;
; ;;; ;;;
; ;; ;;
; ; ; ; ; ;;;; ;;; ;; ;;;
; ; ; ; ; ; ; ; ;; ;
; ; ; ; ; ; ; ; ;
; ; ; ; ;;;;;; ; ; ;
; ; ; ; ; ; ; ;
; ; ; ; ;; ; ; ;
; ;;; ;;; ;;;; ;; ;;;;;;; ;;; ;;;
;
;
;
;
;; Example:
;; > (start 0 100) ; [0,100]
;; 50
;; > (bigger) ; [51,100]
;; 75
;; > (bigger) ; [76,100]
;; 88
;; > (smaller) ; [76,87]
;; 82
;; Number Number -> Number
;; Start a new game in [n,m] and make a guess.
;; > (start 0 100)
;; 50
(define (start n m)
(set! lower (min n m))
(set! upper (max n m))
(guess))
;; Lower and upper bounds on the number
(define lower 1)
(define upper 100)
;; -> Nuber Number
;; Guess half-way between lower and upper bounds.
;; > (begin (start 0 100) (guess))
;; 50
(define (guess)
(quotient (+ lower upper) 2))
;; -> Number
;; Lower the upper bound and guess again.
;; > (begin (start 0 100) (smaller))
;; 24
(define (smaller)
(set! upper (max lower (sub1 (guess))))
(guess))
;; -> Number
;; Raise the lower bound and guess again.
;; > (begin (start 0 100) (bigger))
;; 75
(define (bigger)
(set! lower (min upper (add1 (guess))))
(guess))
;
;
;
;
;
; ;;;;;;; ;
; ; ; ; ;
; ; ; ; ;;; ;;;; ; ;;;;;;; ;;;; ;
; ; ; ; ; ; ; ;; ; ; ;;
; ; ; ; ; ; ;
; ; ;;;;;;; ;;;;; ; ;;;;;
; ; ; ; ; ;
; ; ; ; ; ; ; ; ; ;
; ;;;;; ;;;; ;;;;;; ;;;; ;;;;;;
;
;
;
;
(module+ test
;; basic guesses
(check-equal? (guess) 50)
(check-equal? (start 0 100) 50)
(check-equal? (begin (start 0 100) lower) 0)
(check-equal? (begin (start 0 100) upper) 100)
(check-equal? (begin (start 0 100) (smaller)) 24)
(check-equal? (begin (start 0 000) (smaller)) 0)
(check-equal? (begin (start 0 100) (smaller) lower) 0)
(check-equal? (begin (start 0 100) (smaller) upper) 49)
(check-equal? (begin (start 0 100) (bigger)) 75)
(check-equal? (begin (start 0 000) (bigger)) 0)
;; testing a sequence of interactions with expected intermediate states
(test-begin (start 0 100)
(bigger)
(check-equal? lower 51)
(check-equal? upper 100)
(bigger)
(check-equal? lower 76)
(check-equal? upper 100)
(smaller)
(check-equal? lower 76)
(check-equal? upper 87))
;; doing it all over for negative numbers
(check-equal? (start -100 0) -50)
(check-equal? (begin (start -100 0) lower) -100)
(check-equal? (begin (start -100 0) upper) 0)
(check-equal? (begin (start -100 0) (smaller)) -75)
(check-equal? (begin (start -100 0) (smaller)) -75)
(check-equal? (begin (start -100 0) (smaller) lower) -100)
(check-equal? (begin (start -100 0) (smaller) upper) -51)
(check-equal? (begin (start -100 0) (bigger)) -24)
(check-equal? (begin (start -100 0) (bigger)) -24)
(test-begin (start -100 0)
(bigger)
(check-equal? lower -49)
(check-equal? upper 0)
(bigger)
(check-equal? lower -23)
(check-equal? upper 0)
(smaller)
(check-equal? lower -23)
(check-equal? upper -12))
;; ---------------------------------------------------------------------------
;; testing random properties of our functions
;; Property:
;; For all games starting in [n,m] after any number of moves,
;; lower <= upper.
(define (prop:ordered n m i)
(check-true
(begin (start n m)
(random-moves i)
(<= lower upper))))
;; Property:
;; For all games starting in [n,m], for any number of moves,
;; lower grows up, upper grows down, or they are equal.
(define (prop:monotonic n m i)
(check-true
(begin (start n m)
(for/and ([i (in-range i)])
(define l lower)
(define u upper)
(random-move)
(or (and (< l lower) (= u upper))
(and (= l lower) (> u upper))
(and (= l lower) (= u upper)))))))
;; Number -> Void
;; Move randomly n times.
(define (random-moves i)
(unless (zero? i)
(random-move)
(random-moves (sub1 i))))
;; -> Void
;; Move randomly once.
(define (random-move)
(if (zero? (random 2))
(smaller)
(bigger)))
;; property tests
(for ([i (in-range 1000)])
(prop:ordered (random 1000) (random 1000) (random 100))
(prop:monotonic (random 1000) (random 1000) (random 100)))
;; reset the boundaries to defaults
(start 1 100)
"all tests run")