etl

elixir/etl/.exercism/config.json

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+{
+  "authors": [
+    "rubysolo"
+  ],
+  "contributors": [
+    "andrewsardone",
+    "angelikatyborska",
+    "bartj3",
+    "Cohen-Carlisle",
+    "dalexj",
+    "dantswain",
+    "devonestes",
+    "etrepum",
+    "henrik",
+    "herminiotorres",
+    "jinyeow",
+    "kytrinyx",
+    "lpil",
+    "neenjaw",
+    "parkerl",
+    "pminten",
+    "sotojuan",
+    "Teapane",
+    "waiting-for-dev"
+  ],
+  "files": {
+    "solution": [
+      "lib/etl.ex"
+    ],
+    "test": [
+      "test/etl_test.exs"
+    ],
+    "example": [
+      ".meta/example.ex"
+    ]
+  },
+  "blurb": "Change the data format for scoring a game to more easily add other languages.",
+  "source": "Based on an exercise by the JumpstartLab team for students at The Turing School of Software and Design.",
+  "source_url": "https://turing.edu"
+}

elixir/etl/.exercism/metadata.json

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+{"track":"elixir","exercise":"etl","id":"92b4397f7b3f46c29ffc502cf111495f","url":"https://exercism.org/tracks/elixir/exercises/etl","handle":"negrienko","is_requester":true,"auto_approve":false}

elixir/etl/.formatter.exs

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

elixir/etl/.gitignore

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+# 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").
+etl-*.tar
+

elixir/etl/HELP.md

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+# Help
+
+## Running the tests
+
+From the terminal, change to the base directory of the exercise then execute the tests with:
+
+```bash
+$ mix test
+```
+
+This will execute the test file found in the `test` subfolder -- a file ending in `_test.exs`
+
+Documentation:
+
+* [`mix test` - Elixir's test execution tool](https://hexdocs.pm/mix/Mix.Tasks.Test.html)
+* [`ExUnit` - Elixir's unit test library](https://hexdocs.pm/ex_unit/ExUnit.html)
+
+## Pending tests
+
+In test suites of practice exercises, all but the first test have been tagged to be skipped.
+
+Once you get a test passing, you can unskip the next one by commenting out the relevant `@tag :pending` with a `#` symbol.
+
+For example:
+
+```elixir
+# @tag :pending
+test "shouting" do
+  assert Bob.hey("WATCH OUT!") == "Whoa, chill out!"
+end
+```
+
+If you wish to run all tests at once, you can include all skipped test by using the `--include` flag on the `mix test` command:
+
+```bash
+$ mix test --include pending
+```
+
+Or, you can enable all the tests by commenting out the `ExUnit.configure` line in the file `test/test_helper.exs`.
+
+```elixir
+# ExUnit.configure(exclude: :pending, trace: true)
+```
+
+## Useful `mix test` options
+
+* `test/<FILE>.exs:LINENUM` - runs only a single test, the test from `<FILE>.exs` whose definition is on line `LINENUM`
+* `--failed` - runs only tests that failed the last time they ran
+* `--max-failures` - the suite stops evaluating tests when this number of test failures
+is reached
+* `--seed 0` - disables randomization so the tests in a single file will always be ran
+in the same order they were defined in
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit lib/etl.ex` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Elixir track's documentation](https://exercism.org/docs/tracks/elixir)
+- The [Elixir track's programming category on the forum](https://forum.exercism.org/c/programming/elixir)
+- [Exercism's programming category on the forum](https://forum.exercism.org/c/programming/5)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+If you're stuck on something, it may help to look at some of the [available resources](https://exercism.org/docs/tracks/elixir/resources) out there where answers might be found.

elixir/etl/README.md

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+# ETL
+
+Welcome to ETL on Exercism's Elixir Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Introduction
+
+You work for a company that makes an online multiplayer game called Lexiconia.
+
+To play the game, each player is given 13 letters, which they must rearrange to create words.
+Different letters have different point values, since it's easier to create words with some letters than others.
+
+The game was originally launched in English, but it is very popular, and now the company wants to expand to other languages as well.
+
+Different languages need to support different point values for letters.
+The point values are determined by how often letters are used, compared to other letters in that language.
+
+For example, the letter 'C' is quite common in English, and is only worth 3 points.
+But in Norwegian it's a very rare letter, and is worth 10 points.
+
+To make it easier to add new languages, your team needs to change the way letters and their point values are stored in the game.
+
+## Instructions
+
+Your task is to change the data format of letters and their point values in the game.
+
+Currently, letters are stored in groups based on their score, in a one-to-many mapping.
+
+- 1 point: "A", "E", "I", "O", "U", "L", "N", "R", "S", "T",
+- 2 points: "D", "G",
+- 3 points: "B", "C", "M", "P",
+- 4 points: "F", "H", "V", "W", "Y",
+- 5 points: "K",
+- 8 points: "J", "X",
+- 10 points: "Q", "Z",
+
+This needs to be changed to store each individual letter with its score in a one-to-one mapping.
+
+- "a" is worth 1 point.
+- "b" is worth 3 points.
+- "c" is worth 3 points.
+- "d" is worth 2 points.
+- etc.
+
+As part of this change, the team has also decided to change the letters to be lower-case rather than upper-case.
+
+~~~~exercism/note
+If you want to look at how the data was previously structured and how it needs to change, take a look at the examples in the test suite.
+~~~~
+
+## Source
+
+### Created by
+
+- @rubysolo
+
+### Contributed to by
+
+- @andrewsardone
+- @angelikatyborska
+- @bartj3
+- @Cohen-Carlisle
+- @dalexj
+- @dantswain
+- @devonestes
+- @etrepum
+- @henrik
+- @herminiotorres
+- @jinyeow
+- @kytrinyx
+- @lpil
+- @neenjaw
+- @parkerl
+- @pminten
+- @sotojuan
+- @Teapane
+- @waiting-for-dev
+
+### Based on
+
+Based on an exercise by the JumpstartLab team for students at The Turing School of Software and Design. - https://turing.edu

elixir/etl/lib/etl.ex

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+defmodule ETL do
+  @doc """
+  Transforms an old Scrabble score system to a new one.
+
+  ## Examples
+
+    iex> ETL.transform(%{1 => ["A", "E"], 2 => ["D", "G"]})
+    %{"a" => 1, "d" => 2, "e" => 1, "g" => 2}
+  """
+  @spec transform(map) :: map
+  def transform(input) do
+    for {score, letters} <- input, letter <- letters, into: %{} do
+      {String.downcase(letter), score}
+    end
+  end
+end

elixir/etl/mix.exs

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+defmodule Etl.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :etl,
+      version: "0.1.0",
+      # elixir: "~> 1.8",
+      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

elixir/etl/test/etl_test.exs

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+defmodule ETLTest do
+  use ExUnit.Case
+
+  test "single letter" do
+    old = %{1 => ["A"]}
+    expected = %{"a" => 1}
+
+    assert ETL.transform(old) == expected
+  end
+
+  test "single score with multiple letters" do
+    old = %{1 => ~W(A E I O U)}
+    expected = %{"a" => 1, "e" => 1, "i" => 1, "o" => 1, "u" => 1}
+
+    assert ETL.transform(old) == expected
+  end
+
+  test "multiple scores with multiple letters" do
+    old = %{1 => ["A", "E"], 2 => ["D", "G"]}
+
+    expected = %{
+      "a" => 1,
+      "d" => 2,
+      "e" => 1,
+      "g" => 2
+    }
+
+    assert ETL.transform(old) == expected
+  end
+
+  test "multiple scores with differing numbers of letters" do
+    old = %{
+      1 => ~W(A E I O U L N R S T),
+      2 => ~W(D G),
+      3 => ~W(B C M P),
+      4 => ~W(F H V W Y),
+      5 => ~W(K),
+      8 => ~W(J X),
+      10 => ~W(Q Z)
+    }
+
+    expected = %{
+      "a" => 1,
+      "b" => 3,
+      "c" => 3,
+      "d" => 2,
+      "e" => 1,
+      "f" => 4,
+      "g" => 2,
+      "h" => 4,
+      "i" => 1,
+      "j" => 8,
+      "k" => 5,
+      "l" => 1,
+      "m" => 3,
+      "n" => 1,
+      "o" => 1,
+      "p" => 3,
+      "q" => 10,
+      "r" => 1,
+      "s" => 1,
+      "t" => 1,
+      "u" => 1,
+      "v" => 4,
+      "w" => 4,
+      "x" => 8,
+      "y" => 4,
+      "z" => 10
+    }
+
+    assert ETL.transform(old) == expected
+  end
+end

elixir/etl/test/test_helper.exs

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+ExUnit.start()
+ExUnit.configure(exclude: :pending, trace: true)