Add new practice exercise game-of-life (#1481)

* improve generator

* add game of life

* remove unused variable

* ignore vimeo link

.lycheeignore

@@ -6,3 +6,4 @@ twitter.com
 regexr.com
 papyr.com
 reddit.com
+vimeo.com/53221562

bin/bootstrap_practice_exercise.exs

@@ -1,8 +1,8 @@
 # Generate all files required for a practice exercise.
 # File content is filled as much as possible, but some, including tests, need manual input.
 #
-# Run the following command from the root of the repo:
-# $ elixir bin/boostrap_practice_exercise.exs complex-numbers
+# Do not run directly, instead use this script:
+# $ bin/generate_practice_exercise.sh complex-numbers
 # Pass the name of the exercise (e. g., "complex-numbers") as an argument
 
 Mix.install([
@@ -143,9 +143,6 @@ module =
 
 ## Step 1: create folder structure
 
-Mix.Generator.create_directory("exercises/practice/#{exercise}")
-Mix.Generator.create_directory("exercises/practice/#{exercise}/.docs")
-Mix.Generator.create_directory("exercises/practice/#{exercise}/.meta")
 Mix.Generator.create_directory("exercises/practice/#{exercise}/lib")
 Mix.Generator.create_directory("exercises/practice/#{exercise}/test")
 
@@ -243,38 +240,6 @@ url =
 :inets.start()
 :ssl.start()
 
-# .docs/instructions.md
-{:ok, {_status, _header, description}} =
-  :httpc.request(:get, {url ++ ~c"/description.md", []}, [], [])
-
-Mix.Generator.create_file("exercises/practice/#{exercise}/.docs/instructions.md", description)
-
-# .meta/config.json
-{:ok, {_status, _header, metadata}} =
-  :httpc.request(:get, {url ++ ~c"/metadata.toml", []}, [], [])
-
-metadata =
-  metadata
-  |> to_string
-  |> Toml.decode!()
-
-config = %{
-  authors: [],
-  contributors: [],
-  files: %{
-    solution: ["lib/#{exercise_snake_case}.ex"],
-    test: ["test/#{exercise_snake_case}_test.exs"],
-    example: [".meta/example.ex"]
-  }
-}
-
-config =
-  Map.merge(metadata, config)
-  |> Jason.encode!(pretty: true)
-
-Mix.Generator.create_file("exercises/practice/#{exercise}/.meta/config.json", config)
-IO.puts("Don't forget to add your name and the names of contributors")
-
 # tests and lib files
 {:ok, {_status, _header, data}} =
   :httpc.request(:get, {url ++ ~c"/canonical-data.json", []}, [], [])

bin/generate_practice_exercise.sh

@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+
+# Exit if anything fails.
+set -eo pipefail
+
+# If argument not provided, print usage and exit
+if [ -z "$1" ]; then
+    echo "Usage: bin/generate_practice_exercise.sh <exercise-slug>"
+    exit 1
+fi
+
+SLUG="$1"
+
+# build configlet
+echo "Fetching latest version of configlet..."
+./bin/fetch-configlet
+
+# Preparing config.json
+echo "Adding instructions and configuration files..."
+UUID=$(bin/configlet uuid)
+jq --arg slug "$SLUG" --arg uuid "$UUID" \
+    '.exercises.practice += [{slug: $slug, name: "TODO", uuid: $uuid, practices: [], prerequisites: [], difficulty: 5}]' \
+    config.json > config.json.tmp
+mv config.json.tmp config.json
+
+# Create instructions and config files
+./bin/configlet sync --update --yes --docs --filepaths --metadata --exercise "$SLUG"
+
+# Create Elixir files
+echo "Creating Elixir files..."
+elixir bin/bootstrap_practice_exercise.exs $SLUG
+
+echo "All stub files were created. After implementing the solution, tests and configuration, please run:"
+echo "    elixir bin/check_practice_exercise_order.exs --write"
+echo "    ./bin/configlet sync --update --tests --exercise ${SLUG}"
+echo "    ./bin/configlet fmt --update --yes --exercise ${SLUG}"

config.json

@@ -2313,6 +2313,22 @@
         ],
         "difficulty": 5
       },
+      {
+        "slug": "game-of-life",
+        "name": "Game of Life",
+        "uuid": "32d53ab8-abea-4483-a8cb-ee3b908a9dd7",
+        "practices": [
+          "enum"
+        ],
+        "prerequisites": [
+          "enum",
+          "lists",
+          "pattern-matching",
+          "pipe-operator",
+          "multiple-clause-functions"
+        ],
+        "difficulty": 6
+      },
       {
         "slug": "knapsack",
         "name": "Knapsack",

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/.formatter.exs

@@ -0,0 +1,4 @@
+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]

exercises/practice/game-of-life/.gitignore

@@ -0,0 +1,26 @@
+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where third-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Ignore .fetch files in case you like to edit your project deps locally.
+/.fetch
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+game_of_life-*.tar
+
+# Temporary files, for example, from tests.
+/tmp/

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

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "jiegillet"
+  ],
+  "files": {
+    "solution": [
+      "lib/game_of_life.ex"
+    ],
+    "test": [
+      "test/game_of_life_test.exs"
+    ],
+    "example": [
+      ".meta/example.ex"
+    ]
+  },
+  "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/example.ex

@@ -0,0 +1,44 @@
+defmodule GameOfLife do
+  @doc """
+  Apply the rules of Conway's Game of Life to a grid of cells
+  """
+
+  @spec tick(matrix :: list(list(0 | 1))) :: list(list(0 | 1))
+  def tick([]), do: []
+
+  def tick(matrix) do
+    neighbors = count_neighbors(matrix)
+
+    Enum.zip_with(matrix, neighbors, fn row_matrix, row_neighbor ->
+      Enum.zip_with(row_matrix, row_neighbor, &rule/2)
+    end)
+  end
+
+  defp count_neighbors(matrix) do
+    shift_left = shift_left(matrix)
+    shift_right = shift_right(matrix)
+
+    shifts = [
+      shift_left,
+      shift_right,
+      shift_up(matrix),
+      shift_down(matrix),
+      shift_left |> shift_up(),
+      shift_left |> shift_down(),
+      shift_right |> shift_up(),
+      shift_right |> shift_down()
+    ]
+
+    Enum.zip_with(shifts, fn rows -> Enum.zip_with(rows, &Enum.sum/1) end)
+  end
+
+  defp shift_right(matrix), do: Enum.map(matrix, fn row -> [0 | row] end)
+  defp shift_left(matrix), do: Enum.map(matrix, fn row -> Enum.drop(row, 1) ++ [0] end)
+  defp shift_up([first | rest]), do: rest ++ [Enum.map(first, fn _ -> 0 end)]
+  defp shift_down([first | _] = matrix), do: [Enum.map(first, fn _ -> 0 end) | matrix]
+
+  defp rule(1, 2), do: 1
+  defp rule(1, 3), do: 1
+  defp rule(0, 3), do: 1
+  defp rule(_cell, _live_neighbors), do: 0
+end

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/lib/game_of_life.ex

@@ -0,0 +1,9 @@
+defmodule GameOfLife do
+  @doc """
+  Apply the rules of Conway's Game of Life to a grid of cells
+  """
+
+  @spec tick(matrix :: list(list(0 | 1))) :: list(list(0 | 1))
+  def tick(matrix) do
+  end
+end

exercises/practice/game-of-life/mix.exs

@@ -0,0 +1,28 @@
+defmodule GameOfLife.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :game_of_life,
+      version: "0.1.0",
+      # elixir: "~> 1.10",
+      start_permanent: Mix.env() == :prod,
+      deps: deps()
+    ]
+  end
+
+  # Run "mix help compile.app" to learn about applications.
+  def application do
+    [
+      extra_applications: [:logger]
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [
+      # {:dep_from_hexpm, "~> 0.3.0"},
+      # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
+    ]
+  end
+end