Sync say tests (#435)

Author: BNAndras

exercises/practice/say/.meta/config.json

@@ -1,6 +1,7 @@
 {
   "authors": [
-    "bennn"
+    "bennn",
+    "BNAndras"
   ],
   "contributors": [
     "arguello",

exercises/practice/say/.meta/example.rkt

@@ -1,117 +1,56 @@
-#lang racket/base
-
-;; say : Convert integers to English-language descriptions
-
-;; Implements the basic algorithm.
-;; - Does not use the OSX "say" command to speak the number
-;; - Does not insert "and" between chunks
-
-(require
-  racket/contract
-  (only-in racket/match match-define)
-  (only-in racket/string string-trim))
-
-(define SCALE '#(END thousand million billion trillion))
-;; Supported size classifiers
-
-(define UPPER-BOUND (sub1 (expt 10 (* (vector-length SCALE) 3))))
-;; The largest printable number
-
-(define (scale? v) (for/or ([s (in-vector SCALE)]) (eq? v s)))
-;; Contract for scales
-
-;; Use contracts to enforce all bounds
-(provide (contract-out
-  [step1 (-> (integer-in 0 99) string?)]
-  ;; Convert a positive, 2-digit number to an English string
-
-  [step2 (-> natural-number/c (listof (integer-in 0 999)))]
-  ;; Divide a large positive number into a list of 3-digit (or smaller) chunks
-
-  [step3 (-> (integer-in (- UPPER-BOUND) UPPER-BOUND)
-             (listof (cons/c natural-number/c scale?)))]
-  ;; Break a number into chunks and insert scales between the chunks
-
-  [step4 (-> (integer-in (- UPPER-BOUND) UPPER-BOUND)
-             string?)]
-  ;; Convert a number to an English-language string
-))
-
-;; =============================================================================
-
-(define N<20
-  '#("zero" "one" "two" "three" "four" "five" "six" "seven" "eight" "nine" "ten"
-     "eleven" "twelve" "thirteen" "fourteen" "fifteen" "sixteen" "seventeen"
-     "eighteen" "nineteen"))
-
-(define TENS>10
-  '#("twenty" "thirty" "forty" "fifty" "sixty" "seventy" "eighty" "ninety"))
-
-(define (step1 n)
-  (cond
-   [(< n 20)
-    (vector-ref N<20 n)]
-   [else
-    (define q (quotient n 10))
-    (define r (modulo n 10))
-    (define ten-str (vector-ref TENS>10 (- q 2)))
-    (define one-str (and (not (zero? r)) (vector-ref N<20 r)))
-    (if one-str
-        (string-append ten-str "-" one-str)
-        ten-str)]))
-
-(define (step2 N)
-  (let loop ([acc '()]
-             [n N]  ;; Starts as original & we remove 3 digits each step.
-             [i 0]) ;; Index used to pick a scale
-    (define q (quotient n 1000))
-    (define r (modulo n 1000))
+#lang racket
+
+(provide say)
+
+(define/contract (say number)
+  (-> (and/c exact-nonnegative-integer? (</c 1e12)) string?)
+  (if (zero? number)
+      "zero"
+      (let* ([digits (string->list (number->string number))]
+             [chunks (map list->string (chunk-from-right digits))]
+             [words (map to-words chunks)]
+             [scaled (label-magnitude (reverse words))])
+        (string-join (reverse scaled) " "))))
+
+(define (chunk-from-right chars)
+  (foldr (lambda (char acc)
+           (cond
+             [(empty? acc) (list (list char))]
+             [(< (length (first acc)) 3) (cons (cons char (first acc)) (rest acc))]
+             [else (cons (list char) acc)]))
+         '()
+         chars))
+
+(define (to-words chunk)
+  (let ([number (string->number chunk)])
     (cond
-     [(= n r)
-      ;; Reached fixpoint, stop iteration
-      (cons r acc)]
-     [else
-      ;; Repeat using the quotient
-      (loop (cons r acc) q (add1 i))])))
-
-(define (step3 n)
-  (define (add-scale n acc+i)
-    (match-define (cons acc i) acc+i)
-    (define s (vector-ref SCALE i))
-    (define n+s (cons n s))
-    (cons (cons n+s acc) (add1 i)))
-  (car (foldr add-scale (cons '() 0) (step2 n))))
-
-(define (step4 N)
-  ;; Break N into chunks, convert each chunk+scale to a string
-  (define str*
-    (for/list ([n+s (in-list (step3 (abs N)))])
-      (match-define (cons n s) n+s)
-      (define q (quotient n 100))
-      (define r (modulo n 100))
-      (define n-str
-        (cond
-         [(zero? n)
-          ""]
-         [(< n 100)
-          (step1 r)]
-         [else
-          (define hd (vector-ref N<20 q))
-          (define tl (step1 r))
-          (if (equal? "zero" tl)
-              (string-append hd " hundred")
-              (string-append hd " hundred " tl))]))
-      ;; Don't print a scale for zeros or the last chunk
-      (if (or (eq? s 'END) (zero? n))
-          n-str
-          (string-append n-str (format " ~a " s)))))
-  ;; Use `string-trim` to remove trailing whitespace
-  (define n-str (string-trim (apply string-append str*)))
-  (cond ;; Check for special cases
-   [(zero? N)
-    "zero"]
-   [(negative? N)
-    (string-append "negative " n-str)]
-   [else
-    n-str]))
-
+      [(< number 20) (list-ref first-twenty number)]
+      [(< number 100)
+       (let* ([tens (quotient number 10)]
+              [tens-word (list-ref tens-words tens)]
+              [ones (remainder number 10)]
+              [ones-word (list-ref first-twenty ones)])
+         (if (zero? ones)
+             tens-word
+             (string-append tens-word "-" ones-word)))]
+      [else
+       (let* ([hundreds (quotient number 100)]
+              [hundreds-word (list-ref first-twenty hundreds)]
+              [rest (remainder number 100)]
+              [rest-word (to-words (number->string rest))])
+         (if (string=? rest-word "")
+             (string-append hundreds-word " hundred")
+             (string-append hundreds-word " hundred " rest-word)))])))
+
+(define (label-magnitude words)
+  (for/list ([word words]
+             [magnitude '("" " thousand" " million" " billion")]
+             #:unless (string=? word ""))
+    (string-append word magnitude)))
+
+(define first-twenty
+  '("" "one" "two" "three" "four" "five" "six" "seven" "eight" "nine" "ten"
+    "eleven" "twelve" "thirteen" "fourteen" "fifteen" "sixteen" "seventeen" "eighteen" "nineteen"))
+
+(define tens-words
+  '("" "tens" "twenty" "thirty" "forty" "fifty" "sixty" "seventy" "eighty" "ninety"))

exercises/practice/say/.meta/tests.toml

@@ -24,12 +24,24 @@ description = "twenty"
 [d78601eb-4a84-4bfa-bf0e-665aeb8abe94]
 description = "twenty-two"
 
+[f010d4ca-12c9-44e9-803a-27789841adb1]
+description = "thirty"
+
+[738ce12d-ee5c-4dfb-ad26-534753a98327]
+description = "ninety-nine"
+
 [e417d452-129e-4056-bd5b-6eb1df334dce]
 description = "one hundred"
 
 [d6924f30-80ba-4597-acf6-ea3f16269da8]
 description = "one hundred twenty-three"
 
+[2f061132-54bc-4fd4-b5df-0a3b778959b9]
+description = "two hundred"
+
+[feed6627-5387-4d38-9692-87c0dbc55c33]
+description = "nine hundred ninety-nine"
+
 [3d83da89-a372-46d3-b10d-de0c792432b3]
 description = "one thousand"
 

exercises/practice/say/say-test.rkt

@@ -3,74 +3,65 @@
 (require "say.rkt")
 
 (module+ test
-  (require rackunit rackunit/text-ui)
-
-  (define-syntax-rule (check-equal* f [arg == val] ...)
-    (begin (check-equal? (f arg) val) ...))
-
-  (define-syntax-rule (check-exn* f pat [arg] ...)
-    (begin (check-exn exn:fail:contract? (lambda () (f arg))) ...))
-
-  (define step*
-    (list
-      (test-suite "step1"
-        (check-equal* step1
-         [0 == "zero"]
-         [2 == "two"]
-         [14 == "fourteen"]
-         [50 == "fifty"]
-         [98 == "ninety-eight"]
-         [99 == "ninety-nine"])
-
-        (check-exn* step1
-         [-1]
-         [100]))
-
-      (test-suite "step2"
-        (check-equal* step2
-         [1234567890 == '(1 234 567 890)]
-         [1000000890 == '(1   0   0 890)]
-         [22 == '(22)]
-         [3222 == '(3 222)]
-         [1000231 == '(1 0 231)]
-         [1000 == '(1 0)]))
-
-      (test-suite "step3"
-        (check-equal* step3
-         [3222 == '((3 . thousand) (222 . END))]
-         [901003004111 == '((901 . billion) (3 . million)
-                            (4 . thousand) (111 . END))]
-         [999 == '((999 . END))]
-         [21 == '((21 . END))]
-         [19 == '((19 . END))]
-         [100 == '((100 . END))]
-         [123 == '((123 . END))]
-         [1234567890 == '((1 . billion) (234 . million)
-                          (567 . thousand) (890 . END))]))
-
-      (test-suite "step4"
-        (check-equal* step4
-         [10 == "ten"]
-         [100 == "one hundred"]
-         [10000 == "ten thousand"]
-         [10000000 == "ten million"]
-         [10000000000 == "ten billion"]
-         [10000000000000 == "ten trillion"]
-         [999000000000000 == "nine hundred ninety-nine trillion"]
-         [0 == "zero"]
-         [16 == "sixteen"]
-         [300 == "three hundred"]
-         [440 == "four hundred forty"]
-         [999 == "nine hundred ninety-nine"]
-         [-1 == "negative one"]
-         [22 == "twenty-two"]
-         [123 == "one hundred twenty-three"]
-         [22 == "twenty-two"]
-         [14 == "fourteen"]
-         [50 == "fifty"]
-         [98 == "ninety-eight"]
-         [-432600 == "negative four hundred thirty-two thousand six hundred"]
-         [12345 == "twelve thousand three hundred forty-five"]))))
-
-  (for ([suite (in-list step*)])
-    (run-tests suite)))
+  (require rackunit
+           rackunit/text-ui)
+
+  (define suite
+    (test-suite "say tests"
+
+      (test-equal? "zero" (say 0) "zero")
+
+      (test-equal? "one" (say 1) "one")
+
+      (test-equal? "two" (say 2) "two")
+
+      (test-equal? "fourteen" (say 14) "fourteen")
+
+      (test-equal? "twenty" (say 20) "twenty")
+
+      (test-equal? "twenty-two" (say 22) "twenty-two")
+
+      (test-equal? "thirty" (say 30) "thirty")
+
+      (test-equal? "ninety-nine" (say 99) "ninety-nine")
+
+      (test-equal? "one hundred" (say 100) "one hundred")
+
+      (test-equal? "one hundred twenty-three"
+                   (say 123)
+                   "one hundred twenty-three")
+
+      (test-equal? "two hundred" (say 200) "two hundred")
+
+      (test-equal? "nine hundred ninety-nine"
+                   (say 999)
+                   "nine hundred ninety-nine")
+
+      (test-equal? "one thousand" (say 1000) "one thousand")
+
+      (test-equal? "one thousand two hundred thirty-four"
+                   (say 1234)
+                   "one thousand two hundred thirty-four")
+
+      (test-equal? "one million" (say 1000000) "one million")
+
+      (test-equal? "one million two thousand three hundred forty-five"
+                   (say 1002345)
+                   "one million two thousand three hundred forty-five")
+
+      (test-equal? "one billion" (say 1000000000) "one billion")
+
+      (test-equal?
+       "a big number"
+       (say 987654321123)
+       "nine hundred eighty-seven billion six hundred fifty-four million three hundred twenty-one thousand one hundred twenty-three")
+
+      (test-exn "numbers below zero are out of range"
+                exn:fail?
+                (lambda () (say -1)))
+
+      (test-exn "numbers above 999,999,999,999 are out of range"
+                exn:fail?
+                (lambda () (say 1000000000000)))))
+
+  (run-tests suite))

exercises/practice/say/say.rkt

@@ -1,45 +1,6 @@
 #lang racket
 
-;; Converts integers to English-language descriptions
+(provide say)
 
-;; --- NOTE -------------------------------------------------------------------
-;; The test cases in "say-test.rkt" assume:
-;; - Calling a function with an out-of-range argument triggers a contract error
-;; - That `step3` returns a list of (number, symbol) pairs
-;;
-;; We have provided sample contracts so the tests compile, but you
-;;  will want to edit & strengthen these.
-;;
-;; (For example, things like 0.333 and 7/8 pass the `number?` contract
-;;  but these functions expect integers and natural numbers)
-;; ----------------------------------------------------------------------------
-
-(require racket/contract)
-
-(provide (contract-out
-  [step1 (-> number? string?)]
-  ;; Convert a positive, 2-digit number to an English string
-
-  [step2 (-> number? (listof number?))]
-  ;; Divide a large positive number into a list of 3-digit (or smaller) chunks
-
-  [step3 (-> number? (listof (cons/c number? symbol?)))]
-  ;; Break a number into chunks and insert scales between the chunks
-
-  [step4 (-> number? string?)]
-  ;; Convert a number to an English-language string
-))
-
-;; =============================================================================
-
-(define (step1 n)
-  (error "Please implement 'step1'"))
-
-(define (step2 N)
-  (error "Please implement 'step2'"))
-
-(define (step3 n)
-  (error "Please implement 'step3'"))
-
-(define (step4 N)
-  (error "Please implement 'step4'"))
+(define (say number)
+  (error "Please implement 'say'"))