《Elixir 101》Hello World

最近開始接觸 Elixir 這門語言，語法風格接近 Ruby。而他有一種動靜皆備的特性，老實說還蠻吸引我的。

In addition to the Elixir file extension .ex, Elixir also supports .exs files for scripting. Elixir treats both files exactly the same way, the only difference is in intention. .ex files are meant to be compiled while .exs files are used for scripting. When executed, both extensions compile and load their modules into memory, although only .ex files write their bytecode to disk in the format of .beam files.

第一種：直接輸入指令

$ iex
Erlang/OTP 21 [erts-10.0.5] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe] [dtrace]

Interactive Elixir (1.7.2) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> IO.puts("Hello World")
Hello World
:ok
iex(2)>

$ iex
Erlang/OTP 21 [erts-10.0.5] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe] [dtrace]

Interactive Elixir (1.7.2) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> IO.
ANSI                    Stream                  StreamError
binread/1               binread/2               binstream/2
binwrite/1              binwrite/2              chardata_to_string/1
getn/1                  getn/2                  getn/3
gets/1                  gets/2                  inspect/1
inspect/2               inspect/3               iodata_length/1
iodata_to_binary/1      puts/1                  puts/2
read/1                  read/2                  stream/2
warn/1                  warn/2                  write/1
write/2
iex(1)> IO.

第二種：執行檔案

IO.puts("Hello World")

$ elixir hello.ex
Hello World

第三種：模組引用

$ mix new hello-world
** (Mix) Application name must start with a lowercase ASCII letter, followed by lowercase ASCII letters, numbers, or underscores, got: "hello-world". The application name is inferred from the path, if you'd like to explicitly name the application then use the "--app APP" option

$ mix new helloWorld
** (Mix) Application name must start with a lowercase ASCII letter, followed by lowercase ASCII letters, numbers, or underscores, got: "helloWorld". The application name is inferred from the path, if you'd like to explicitly name the application then use the "--app APP" option

$ mix new hello_world
* creating README.md
* creating .formatter.exs
* creating .gitignore
* creating mix.exs
* creating config
* creating config/config.exs
* creating lib
* creating lib/hello_world.ex
* creating test
* creating test/test_helper.exs
* creating test/hello_world_test.exs

Your Mix project was created successfully.
You can use "mix" to compile it, test it, and more:

    cd hello_world
    mix test

Run "mix help" for more commands.

defmodule HelloWorld do
  @moduledoc """
  Documentation for HelloWorld.
  """

  @doc """
  Hello world.

  ## Examples

      iex> HelloWorld.hello()
      :world

  """
  def hello do
    :world
  end
end

$ cd hello_world
$ iex -S mix
Erlang/OTP 21 [erts-10.0.5] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe] [dtrace]

Compiling 1 file (.ex)
Generated hello_world app
Interactive Elixir (1.7.2) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)>

Compiling 1 file (.ex)
Generated hello_world app

iex(1)> HelloWorld.hello()
:world
iex(2)>