roman numerals elixir

elixir/roman-numerals/.exercism/metadata.json

@@ -0,0 +1 @@
+{"track":"elixir","exercise":"roman-numerals","id":"25ed35ad01214047827de019945b902d","url":"https://exercism.io/my/solutions/25ed35ad01214047827de019945b902d","handle":"Xevion","is_requester":true,"auto_approve":false}

elixir/roman-numerals/.formatter.exs

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

elixir/roman-numerals/.gitignore

@@ -0,0 +1,24 @@
+# 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").
+roman_numerals-*.tar
+

elixir/roman-numerals/README.md

@@ -0,0 +1,85 @@
+# Roman Numerals
+
+Write a function to convert from normal numbers to Roman Numerals.
+
+The Romans were a clever bunch. They conquered most of Europe and ruled
+it for hundreds of years. They invented concrete and straight roads and
+even bikinis. One thing they never discovered though was the number
+zero. This made writing and dating extensive histories of their exploits
+slightly more challenging, but the system of numbers they came up with
+is still in use today. For example the BBC uses Roman numerals to date
+their programmes.
+
+The Romans wrote numbers using letters - I, V, X, L, C, D, M. (notice
+these letters have lots of straight lines and are hence easy to hack
+into stone tablets).
+
+```text
+ 1  => I
+10  => X
+ 7  => VII
+```
+
+There is no need to be able to convert numbers larger than about 3000.
+(The Romans themselves didn't tend to go any higher)
+
+Wikipedia says: Modern Roman numerals ... are written by expressing each
+digit separately starting with the left most digit and skipping any
+digit with a value of zero.
+
+To see this in practice, consider the example of 1990.
+
+In Roman numerals 1990 is MCMXC:
+
+1000=M
+900=CM
+90=XC
+
+2008 is written as MMVIII:
+
+2000=MM
+8=VIII
+
+See also: http://www.novaroma.org/via_romana/numbers.html
+
+## Running tests
+
+Execute the tests with:
+
+```bash
+$ mix test
+```
+
+### Pending tests
+
+In the test suites, all but the first test have been 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
+```
+
+Or, you can enable all the tests by commenting out the
+`ExUnit.configure` line in the test suite.
+
+```elixir
+# ExUnit.configure exclude: :pending, trace: true
+```
+
+If you're stuck on something, it may help to look at some of
+the [available resources](https://exercism.io/tracks/elixir/resources)
+out there where answers might be found.
+
+## Source
+
+The Roman Numeral Kata [http://codingdojo.org/cgi-bin/index.pl?KataRomanNumerals](http://codingdojo.org/cgi-bin/index.pl?KataRomanNumerals)
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.

elixir/roman-numerals/lib/roman_numerals.ex

@@ -0,0 +1,39 @@
+defmodule RomanNumerals do
+  @values %{
+    "I" => 1,
+    "IV" => 4,
+    "V" => 5,
+    "IX" => 9,
+    "X" => 10,
+    "XL" => 40,
+    "L" => 50,
+    "XC" => 90,
+    "C" => 100,
+    "CD" => 400,
+    "D" => 500,
+    "CM" => 900,
+    "M" => 1000
+  }
+
+  @doc """
+  Convert the number to a roman number.
+  """
+  @spec numeral(pos_integer) :: String.t()
+  def numeral(number) do
+    number
+    |> Stream.unfold(fn
+      0 -> nil
+      n -> get_max(n)
+    end)
+    |> Enum.join()
+  end
+
+  defp get_max(n) do
+    numeral =
+      Map.keys(@values)
+      |> Enum.filter(&(Map.get(@values, &1) <= n))
+      |> Enum.max_by(&Map.get(@values, &1))
+
+    {numeral, n - Map.get(@values, numeral)}
+  end
+end

elixir/roman-numerals/mix.exs

@@ -0,0 +1,28 @@
+defmodule RomanNumerals.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :roman_numerals,
+      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/roman-numerals/test/roman_numerals_test.exs

@@ -0,0 +1,93 @@
+defmodule RomanNumeralsTest do
+  use ExUnit.Case
+
+  # @tag :pending
+  test "1" do
+    assert RomanNumerals.numeral(1) == "I"
+  end
+
+  @tag :pending
+  test "2" do
+    assert RomanNumerals.numeral(2) == "II"
+  end
+
+  @tag :pending
+  test "3" do
+    assert RomanNumerals.numeral(3) == "III"
+  end
+
+  @tag :pending
+  test "4" do
+    assert RomanNumerals.numeral(4) == "IV"
+  end
+
+  @tag :pending
+  test "5" do
+    assert RomanNumerals.numeral(5) == "V"
+  end
+
+  @tag :pending
+  test "6" do
+    assert RomanNumerals.numeral(6) == "VI"
+  end
+
+  @tag :pending
+  test "9" do
+    assert RomanNumerals.numeral(9) == "IX"
+  end
+
+  @tag :pending
+  test "27" do
+    assert RomanNumerals.numeral(27) == "XXVII"
+  end
+
+  @tag :pending
+  test "48" do
+    assert RomanNumerals.numeral(48) == "XLVIII"
+  end
+
+  @tag :pending
+  test "59" do
+    assert RomanNumerals.numeral(59) == "LIX"
+  end
+
+  @tag :pending
+  test "93" do
+    assert RomanNumerals.numeral(93) == "XCIII"
+  end
+
+  @tag :pending
+  test "141" do
+    assert RomanNumerals.numeral(141) == "CXLI"
+  end
+
+  @tag :pending
+  test "163" do
+    assert RomanNumerals.numeral(163) == "CLXIII"
+  end
+
+  @tag :pending
+  test "402" do
+    assert RomanNumerals.numeral(402) == "CDII"
+  end
+
+  @tag :pending
+  test "575" do
+    assert RomanNumerals.numeral(575) == "DLXXV"
+  end
+
+  @tag :pending
+  test "911" do
+    assert RomanNumerals.numeral(911) == "CMXI"
+  end
+
+  @tag :pending
+  test "1024" do
+    assert RomanNumerals.numeral(1024) == "MXXIV"
+  end
+
+  @tag :pending
+  test "3000" do
+    assert RomanNumerals.numeral(3000) == "MMM"
+  end
+end

elixir/roman-numerals/test/test_helper.exs

@@ -0,0 +1,2 @@
+ExUnit.start()
+# ExUnit.configure(exclude: :pending, trace: true)