add hello world properly, add rna-transcription (elixir is neat!)

elixir/hello-world/.formatter.exs

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

elixir/hello-world/.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").
+hello_world-*.tar
+

elixir/hello-world/lib/hello_world.ex

@@ -0,0 +1,9 @@
+defmodule HelloWorld do
+  @doc """
+  Simply returns "Hello, World!"
+  """
+  @spec hello :: String.t()
+  def hello do
+    "Hello, World!"
+  end
+end

elixir/hello-world/mix.exs

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+defmodule HelloWorld.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :hello_world,
+      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/hello-world/test/hello_world_test.exs

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+defmodule HelloWorldTest do
+  use ExUnit.Case
+
+  test "says 'Hello, World!'" do
+    assert HelloWorld.hello() == "Hello, World!"
+  end
+end

elixir/hello-world/test/test_helper.exs

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