Add Game of Life exercise (#1227)

config.json

@@ -334,6 +334,15 @@
         "difficulty": 7,
         "topics": []
       },
+      {
+        "slug": "game-of-life",
+        "name": "Game of Life",
+        "uuid": "eb221634-15c6-463c-8268-54a3c3aa0c66",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 7,
+        "topics": []
+      },
       {
         "slug": "perfect-numbers",
         "name": "Perfect Numbers",

exercises/practice/game-of-life/.docs/instructions.md

@@ -0,0 +1,11 @@
+# Instructions
+
+After each generation, the cells interact with their eight neighbors, which are cells adjacent horizontally, vertically, or diagonally.
+
+The following rules are applied to each cell:
+
+- Any live cell with two or three live neighbors lives on.
+- Any dead cell with exactly three live neighbors becomes a live cell.
+- All other cells die or stay dead.
+
+Given a matrix of 1s and 0s (corresponding to live and dead cells), apply the rules to each cell, and return the next generation.

exercises/practice/game-of-life/.docs/introduction.md

@@ -0,0 +1,9 @@
+# Introduction
+
+[Conway's Game of Life][game-of-life] is a fascinating cellular automaton created by the British mathematician John Horton Conway in 1970.
+
+The game consists of a two-dimensional grid of cells that can either be "alive" or "dead."
+
+After each generation, the cells interact with their eight neighbors via a set of rules, which define the new generation.
+
+[game-of-life]: https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life

exercises/practice/game-of-life/.meta/config.json

@@ -0,0 +1,23 @@
+{
+  "authors": [
+    "tofische"
+  ],
+  "files": {
+    "solution": [
+      "src/GameOfLife.hs",
+      "package.yaml"
+    ],
+    "test": [
+      "test/Tests.hs"
+    ],
+    "example": [
+      ".meta/examples/success-standard/src/GameOfLife.hs"
+    ],
+    "invalidator": [
+      "stack.yaml"
+    ]
+  },
+  "blurb": "Implement Conway's Game of Life.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/Conway%27s_Game_of_Life"
+}

exercises/practice/game-of-life/.meta/examples/success-standard/package.yaml

@@ -0,0 +1,16 @@
+name: food-chain
+
+dependencies:
+  - base
+
+library:
+  exposed-modules: GameOfLife
+  source-dirs: src
+
+tests:
+  test:
+    main: Tests.hs
+    source-dirs: test
+    dependencies:
+      - game-of-life
+      - hspec

exercises/practice/game-of-life/.meta/examples/success-standard/src/GameOfLife.hs

@@ -0,0 +1,22 @@
+module GameOfLife (tick) where
+
+import Data.Maybe (mapMaybe)
+
+tick :: [[Int]] -> [[Int]]
+tick matrix = [[ nextGen x (i, j)
+               | (j, x ) <- zip [0..] xs  ]
+               | (i, xs) <- zip [0..] matrix ]
+    where
+        living = length . filter (== 1) . mapMaybe (`lookup` cells) . neighbors
+
+        neighbors (i, j) = [ (i - 1, j - 1), (i - 1, j), (i - 1, j + 1)
+                           , (i    , j - 1),             (i    , j + 1)
+                           , (i + 1, j - 1), (i + 1, j), (i + 1, j + 1) ]
+
+        nextGen cell position =
+            let around = living position in
+            if (cell == 1 && (around == 2 || around == 3)) || (cell == 0 && around == 3) then 1 else 0
+
+        cells = [ ((i, j), x)
+                | (i, xs) <- zip [0 :: Int ..] matrix
+                , (j, x ) <- zip [0 :: Int ..] xs  ]

exercises/practice/game-of-life/.meta/tests.toml

@@ -0,0 +1,34 @@
+# 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.
+
+[ae86ea7d-bd07-4357-90b3-ac7d256bd5c5]
+description = "empty matrix"
+
+[4ea5ccb7-7b73-4281-954a-bed1b0f139a5]
+description = "live cells with zero live neighbors die"
+
+[df245adc-14ff-4f9c-b2ae-f465ef5321b2]
+description = "live cells with only one live neighbor die"
+
+[2a713b56-283c-48c8-adae-1d21306c80ae]
+description = "live cells with two live neighbors stay alive"
+
+[86d5c5a5-ab7b-41a1-8907-c9b3fc5e9dae]
+description = "live cells with three live neighbors stay alive"
+
+[015f60ac-39d8-4c6c-8328-57f334fc9f89]
+description = "dead cells with three live neighbors become alive"
+
+[2ee69c00-9d41-4b8b-89da-5832e735ccf1]
+description = "live cells with four or more neighbors die"
+
+[a79b42be-ed6c-4e27-9206-43da08697ef6]
+description = "bigger matrix"

exercises/practice/game-of-life/package.yaml

@@ -0,0 +1,21 @@
+name: game-of-life
+version: 1.0.0.0
+
+dependencies:
+  - base
+
+library:
+  exposed-modules: GameOfLife
+  source-dirs: src
+  ghc-options: -Wall
+  # dependencies:
+  # - foo       # List here the packages you
+  # - bar       # want to use in your solution.
+
+tests:
+  test:
+    main: Tests.hs
+    source-dirs: test
+    dependencies:
+      - game-of-life
+      - hspec

exercises/practice/game-of-life/src/GameOfLife.hs

@@ -0,0 +1,4 @@
+module GameOfLife (tick) where
+
+tick :: [[Int]] -> [[Int]]
+tick = error "You need to implement this function."

exercises/practice/game-of-life/stack.yaml

@@ -0,0 +1 @@
+resolver: lts-20.18

exercises/practice/game-of-life/test/Tests.hs

@@ -0,0 +1,125 @@
+{-# OPTIONS_GHC -fno-warn-type-defaults #-}
+{-# LANGUAGE RecordWildCards #-}
+
+import Data.Foldable     (for_)
+import Test.Hspec        (Spec, describe, it, shouldBe)
+import Test.Hspec.Runner (configFailFast, defaultConfig, hspecWith)
+
+import GameOfLife (tick)
+
+main :: IO ()
+main = hspecWith defaultConfig {configFailFast = True} specs
+
+specs :: Spec
+specs = describe "tick" $ for_ cases test
+  where
+
+    test Case{..} = it description assertion
+      where
+        assertion = tick matrix `shouldBe` expected
+
+data Case = Case { description :: String
+                 , matrix      :: [[Int]]
+                 , expected    :: [[Int]]
+                 }
+
+cases :: [Case]
+cases = [ Case { description = "Empty matrix"
+               , matrix      = []
+               , expected    = []
+               }
+        , Case { description = "Live cells with zero live neighbors die"
+               , matrix      = [
+                                [0, 0, 0],
+                                [0, 1, 0],
+                                [0, 0, 0]
+                               ]
+               , expected    = [
+                                [0, 0, 0],
+                                [0, 0, 0],
+                                [0, 0, 0]
+                               ]
+               }
+        , Case { description = "Live cells with only one live neighbor die"
+               , matrix      = [
+                                [0, 0, 0],
+                                [0, 1, 0],
+                                [0, 1, 0]
+                               ]
+               , expected    = [
+                                [0, 0, 0],
+                                [0, 0, 0],
+                                [0, 0, 0]
+                               ]
+               }
+        , Case { description = "Live cells with two live neighbors stay alive"
+               , matrix      = [
+                                [1, 0, 1],
+                                [1, 0, 1],
+                                [1, 0, 1]
+                               ]
+               , expected    = [
+                                [0, 0, 0],
+                                [1, 0, 1],
+                                [0, 0, 0]
+                               ]
+               }
+        , Case { description = "Live cells with three live neighbors stay alive"
+               , matrix      = [
+                                [0, 1, 0],
+                                [1, 0, 0],
+                                [1, 1, 0]
+                               ]
+               , expected    = [
+                                [0, 0, 0],
+                                [1, 0, 0],
+                                [1, 1, 0]
+                               ]
+               }
+        , Case { description = "Dead cells with three live neighbors become alive"
+               , matrix      = [
+                                [1, 1, 0],
+                                [0, 0, 0],
+                                [1, 0, 0]
+                               ]
+               , expected    = [
+                                [0, 0, 0],
+                                [1, 1, 0],
+                                [0, 0, 0]
+                               ]
+               }
+        , Case { description = "Live cells with four or more neighbors die"
+               , matrix      = [
+                                [1, 1, 1],
+                                [1, 1, 1],
+                                [1, 1, 1]
+                               ]
+               , expected    = [
+                                [1, 0, 1],
+                                [0, 0, 0],
+                                [1, 0, 1]
+                               ]
+               }
+        , Case { description = "Bigger matrix"
+               , matrix      = [
+                                [1, 1, 0, 1, 1, 0, 0, 0],
+                                [1, 0, 1, 1, 0, 0, 0, 0],
+                                [1, 1, 1, 0, 0, 1, 1, 1],
+                                [0, 0, 0, 0, 0, 1, 1, 0],
+                                [1, 0, 0, 0, 1, 1, 0, 0],
+                                [1, 1, 0, 0, 0, 1, 1, 1],
+                                [0, 0, 1, 0, 1, 0, 0, 1],
+                                [1, 0, 0, 0, 0, 0, 1, 1]
+                               ]
+               , expected    = [
+                                [1, 1, 0, 1, 1, 0, 0, 0],
+                                [0, 0, 0, 0, 0, 1, 1, 0],
+                                [1, 0, 1, 1, 1, 1, 0, 1],
+                                [1, 0, 0, 0, 0, 0, 0, 1],
+                                [1, 1, 0, 0, 1, 0, 0, 1],
+                                [1, 1, 0, 1, 0, 0, 0, 1],
+                                [1, 0, 0, 0, 0, 0, 0, 0],
+                                [0, 0, 0, 0, 0, 0, 1, 1]
+                               ]
+               }
+        ]