elixir_installation.md

theme: Merriweather2, 1

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Elixir.tw

https://www.facebook.com/groups/elixir.tw/ https://www.meetup.com/Taipei-Elixir-Erlang-Meetup-Group/

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[fit] Elixir installation party

http://bit.do/elixir_install

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Levarage Erlang

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Distribute

Light weight process

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Java, PHP, Python, JavaScript, Ruby

with multi core CPU

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C#¹

300µs per process 50µs per message

Erlang

1µs up to 2,500 processe 3µs up to 30,00 processes 0.8µs per message

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process in Erlang/Elixir =~ object instance in OO application

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We do not have ONE web-server handling 2 millions sessions. We have 2 million webservers handling one session each.²

• Joe Armstrong

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Fault-tolerant

* Let it crash

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Update on the fly, literally.

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[fit] 2. Elixir Syntax Highlight

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Intuitive syntax like Ruby

defmodule Math do
  def sum(a, b) do
    a + b
  end
end

Math.sum(1, 2)  #=> 3

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Pattern matching

What's the "=" means, seriously?

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Pattern matching basic

x = 1

# Ruby x, x, y = [1, 2, 3] # => x = 2, y = 3

[x, x, y] = [1, 2, 3] # => Error

[x, x, y] = [1, 1, 3] # => x = 1, y = 3

{m, "bar", n} = {"foo", "bar", "baz"} => m = "foo", n = "baz"

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Mathmatical function

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Pattern matching

defmodule Factorial do
  def calc(0), do: 1
  def calc(val), do: val * calc(val - 1)
end

Factorial.calc(100)

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Pattern matching, contd.

def parse(html =
            %{head: head = %{title: title, meta: _},
            body: body})
    when is_bitstring(title) do
    # body => "Hello world"
    # title => "foo"
    # head => %{title: "foo", meta: "bar"}
    # html => %{head: %{title: "foo", meta: "bar"}, body: "Hello world"}
end

parse(%{head: %{title: "foo", meta: "bar"}, body: "Hello world"})

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Pipe operator: |>

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Problem: useless temp variable

response = get_response(request)
body = parse_body(response, :html)
html = render(body)

html = render(parse_body(get_response(request), :html))

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Pipe operator: |>

html =
  request
  |> get_response()
  |> parse_body(:html)
  |> render()

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Functional

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Map, Filter and Reduce

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Functional modules:

• Enum: map, reduce, filter, zip, scan
• Stream: lazy evaluation

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OTP modules:

• GenServer, Supervisor
• Task: Partially GenServer
• Agent: Another side of GenServer
• Flow: Back-preasure concurrent base on GenState

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Meta-programming:

marco, quote, unquote

The ability to manipulate AST

iex> quote do: 1 * 2 + 3

{:+, [context: Elixir, import: Kernel],
[{:*, [context: Elixir, import: Kernel], [1, 2]}, 3]}

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doctest

defmodule Num do
  @doc """
  Demonstrate doctest feature
  ## Example
    iex> Num.is_even?(1)
    true
  """
  def is_even?(num) do
    rem(num, 2) == 0
  end
end

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doc part

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test part

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Trinity

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3. Phoenix

TODO: mickey

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4. Nerves

The IOT framework of Elixir

https://github.com/nerves-project

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installation

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Poncho project

.
├── firmware
│   ├── _build
│   ├── config
│   ├── deps
│   ├── lib
│   ├── mix.exs
│   └── mix.lock.rpi3
└── ui
    ├── assets
    ├── config
    ├── deps
    ├── lib
    ├── mix.exs
    └── priv

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Barebone: Firmware

export MIX_TARGET=rpi3
mix deps.get
mix firmware
mix firmware.burn

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Wireless update

{:nerves_firmware_http, "~> 0.4"}

mix firmware.push 192.168.1.100 --target rpi3

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學習資源

• Elixir.tw Facebook:

• Elixir.tw slack: https://elixirtw.herokuapp.com/

• Elixir slack

• Pragmatic bookshelf

• Manning

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Thanks

Any Questions?

Footnotes

1. 2003's data ↩

2. http://goo.gl/IlcNTF ↩