Add Bowling for Racket (#412)

Author: blakelewis

config.json

@@ -742,6 +742,14 @@
         ],
         "prerequisites": [],
         "difficulty": 8
+      },
+      {
+        "slug": "bowling",
+        "name": "Bowling",
+        "uuid": "f6ca2cb9-f169-4c3e-8a64-6d3326b01d70",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 6
       }
     ]
   },

exercises/practice/bowling/.docs/instructions.md

@@ -0,0 +1,56 @@
+# Instructions
+
+Score a bowling game.
+
+Bowling is a game where players roll a heavy ball to knock down pins arranged in a triangle.
+Write code to keep track of the score of a game of bowling.
+
+## Scoring Bowling
+
+The game consists of 10 frames.
+A frame is composed of one or two ball throws with 10 pins standing at frame initialization.
+There are three cases for the tabulation of a frame.
+
+- An open frame is where a score of less than 10 is recorded for the frame.
+  In this case the score for the frame is the number of pins knocked down.
+
+- A spare is where all ten pins are knocked down by the second throw.
+  The total value of a spare is 10 plus the number of pins knocked down in their next throw.
+
+- A strike is where all ten pins are knocked down by the first throw.
+  The total value of a strike is 10 plus the number of pins knocked down in the next two throws.
+  If a strike is immediately followed by a second strike, then the value of the first strike cannot be determined until the ball is thrown one more time.
+
+Here is a three frame example:
+
+|  Frame 1   |  Frame 2   |     Frame 3      |
+| :--------: | :--------: | :--------------: |
+| X (strike) | 5/ (spare) | 9 0 (open frame) |
+
+Frame 1 is (10 + 5 + 5) = 20
+
+Frame 2 is (5 + 5 + 9) = 19
+
+Frame 3 is (9 + 0) = 9
+
+This means the current running total is 48.
+
+The tenth frame in the game is a special case.
+If someone throws a spare or a strike then they get one or two fill balls respectively.
+Fill balls exist to calculate the total of the 10th frame.
+Scoring a strike or spare on the fill ball does not give the player more fill balls.
+The total value of the 10th frame is the total number of pins knocked down.
+
+For a tenth frame of X1/ (strike and a spare), the total value is 20.
+
+For a tenth frame of XXX (three strikes), the total value is 30.
+
+## Requirements
+
+Write code to keep track of the score of a game of bowling.
+It should support two operations:
+
+- `roll(pins : int)` is called each time the player rolls a ball.
+  The argument is the number of pins knocked down.
+- `score() : int` is called only at the very end of the game.
+  It returns the total score for that game.

exercises/practice/bowling/.meta/config.json

@@ -0,0 +1,17 @@
+{
+  "authors": ["blakelewis"],
+  "files": {
+    "solution": [
+      "bowling.rkt"
+    ],
+    "test": [
+      "bowling-test.rkt"
+    ],
+    "example": [
+      ".meta/example.rkt"
+    ]
+  },
+  "blurb": "Score a bowling game.",
+  "source": "The Bowling Game Kata from UncleBob",
+  "source_url": "https://web.archive.org/web/20221001111000/http://butunclebob.com/ArticleS.UncleBob.TheBowlingGameKata"
+}

exercises/practice/bowling/.meta/example.rkt

@@ -0,0 +1,59 @@
+#lang racket
+
+(provide game%)
+
+(define game%
+  (class object%
+    (super-new)
+    (define frame 1)
+    (define ball 0)
+    (define standing 10)
+    (define total 0)
+    (define bonus1 0)
+    (define bonus2 0)
+    (define fill-balls 0)
+
+    (define (game-over?)
+       (and (> frame 10) (zero? fill-balls)))
+
+    (define (new-frame)
+       (set! frame (add1 frame))
+       (set! standing 10))
+
+    (define (add-roll pins)
+      (define bonus
+         (cond [(> frame 10) (max 0 (- bonus1 (- frame 10)))]
+               [(zero? ball) bonus1]
+               [else bonus2]))
+
+      (if (zero? ball) (set! bonus1 0) (set! bonus2 0))
+
+      (set! total (+ total (* pins (add1 bonus))))
+      (set! standing (- standing pins))
+      (cond
+         [(zero? standing)
+            (cond
+              [(zero? ball)		; strike
+                 (set! bonus1 (add1 bonus2))
+                 (set! bonus2 1)
+                 (when (= frame 10) (set! fill-balls 2))]
+              [else			; spare
+                 (set! bonus1 1)
+                 (when (= frame 10) (set! fill-balls 1))
+                 (set! ball 0)])]
+          [else				; ordinary roll
+             (set! ball (- 1 ball))])
+      (when (> frame 10) (set! fill-balls (sub1 fill-balls)))
+      (when (zero? ball) (new-frame)))
+
+    (define/public (roll pins)
+      (when (or (< pins 0) (> pins standing))
+        (error "Invalid number of pins"))
+      (when (game-over?)
+        (error "Game is over"))
+      (add-roll pins))
+
+    (define/public (score)
+       (cond
+         [(game-over?) total]
+         [else (error "Game is not over")]))))

exercises/practice/bowling/.meta/tests.toml

@@ -0,0 +1,103 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[656ae006-25c2-438c-a549-f338e7ec7441]
+description = "should be able to score a game with all zeros"
+
+[f85dcc56-cd6b-4875-81b3-e50921e3597b]
+description = "should be able to score a game with no strikes or spares"
+
+[d1f56305-3ac2-4fe0-8645-0b37e3073e20]
+description = "a spare followed by zeros is worth ten points"
+
+[0b8c8bb7-764a-4287-801a-f9e9012f8be4]
+description = "points scored in the roll after a spare are counted twice"
+
+[4d54d502-1565-4691-84cd-f29a09c65bea]
+description = "consecutive spares each get a one roll bonus"
+
+[e5c9cf3d-abbe-4b74-ad48-34051b2b08c0]
+description = "a spare in the last frame gets a one roll bonus that is counted once"
+
+[75269642-2b34-4b72-95a4-9be28ab16902]
+description = "a strike earns ten points in a frame with a single roll"
+
+[037f978c-5d01-4e49-bdeb-9e20a2e6f9a6]
+description = "points scored in the two rolls after a strike are counted twice as a bonus"
+
+[1635e82b-14ec-4cd1-bce4-4ea14bd13a49]
+description = "consecutive strikes each get the two roll bonus"
+
+[e483e8b6-cb4b-4959-b310-e3982030d766]
+description = "a strike in the last frame gets a two roll bonus that is counted once"
+
+[9d5c87db-84bc-4e01-8e95-53350c8af1f8]
+description = "rolling a spare with the two roll bonus does not get a bonus roll"
+
+[576faac1-7cff-4029-ad72-c16bcada79b5]
+description = "strikes with the two roll bonus do not get bonus rolls"
+
+[efb426ec-7e15-42e6-9b96-b4fca3ec2359]
+description = "last two strikes followed by only last bonus with non strike points"
+
+[72e24404-b6c6-46af-b188-875514c0377b]
+description = "a strike with the one roll bonus after a spare in the last frame does not get a bonus"
+
+[62ee4c72-8ee8-4250-b794-234f1fec17b1]
+description = "all strikes is a perfect game"
+
+[1245216b-19c6-422c-b34b-6e4012d7459f]
+description = "rolls cannot score negative points"
+
+[5fcbd206-782c-4faa-8f3a-be5c538ba841]
+description = "a roll cannot score more than 10 points"
+
+[fb023c31-d842-422d-ad7e-79ce1db23c21]
+description = "two rolls in a frame cannot score more than 10 points"
+
+[6082d689-d677-4214-80d7-99940189381b]
+description = "bonus roll after a strike in the last frame cannot score more than 10 points"
+
+[e9565fe6-510a-4675-ba6b-733a56767a45]
+description = "two bonus rolls after a strike in the last frame cannot score more than 10 points"
+
+[2f6acf99-448e-4282-8103-0b9c7df99c3d]
+description = "two bonus rolls after a strike in the last frame can score more than 10 points if one is a strike"
+
+[6380495a-8bc4-4cdb-a59f-5f0212dbed01]
+description = "the second bonus rolls after a strike in the last frame cannot be a strike if the first one is not a strike"
+
+[2b2976ea-446c-47a3-9817-42777f09fe7e]
+description = "second bonus roll after a strike in the last frame cannot score more than 10 points"
+
+[29220245-ac8d-463d-bc19-98a94cfada8a]
+description = "an unstarted game cannot be scored"
+
+[4473dc5d-1f86-486f-bf79-426a52ddc955]
+description = "an incomplete game cannot be scored"
+
+[2ccb8980-1b37-4988-b7d1-e5701c317df3]
+description = "cannot roll if game already has ten frames"
+
+[4864f09b-9df3-4b65-9924-c595ed236f1b]
+description = "bonus rolls for a strike in the last frame must be rolled before score can be calculated"
+
+[537f4e37-4b51-4d1c-97e2-986eb37b2ac1]
+description = "both bonus rolls for a strike in the last frame must be rolled before score can be calculated"
+
+[8134e8c1-4201-4197-bf9f-1431afcde4b9]
+description = "bonus roll for a spare in the last frame must be rolled before score can be calculated"
+
+[9d4a9a55-134a-4bad-bae8-3babf84bd570]
+description = "cannot roll after bonus roll for spare"
+
+[d3e02652-a799-4ae3-b53b-68582cc604be]
+description = "cannot roll after bonus rolls for strike"