Let's create stateful systems, by Elixir

Transcript

1. 1.

   Let's create stateful systems, by Elixir

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   . ｡oO( さっちゃんですよヾ( 〃l _ l) ﾉﾞ☆)

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   I'll show you a number.

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   2

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   Two

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   Ⅱ

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   ⼆

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   2 is a number of collison & collaboration.

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   I & you hot & ice stand up & lie

   down inside & outside
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    stateless & stateful

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    Function is stateless. f : x -> y e.g. Web

    server
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    Dialogue is stateful. Alice : X. Bob : Y. Alice

    : X. Bob : Z. Most of the system is stateful.
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    Elixir

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    Elixir is a functional programming language. Functional programming is stateless.

    All data of Elixir is immutable. [x, 3, x] = Enum.map([1,2,1], &(&1 + 1)) assert 2 == x // Many lines that don't reassign to `x`. assert 2 == x
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    Elixir has processes. 29 = Task.async(fn -> 29 end) |>

    Task.await
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    Process has state. agent = Agent.start_link(fn -> 29 end) 29

    = Agent.get(agent, &(&1)) Agent.update(agent, &(&1 + 13)) 42 = Agent.get(agent, &(&1))
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    State should be updated in a transaction. State shold interact

    & isolate each other. Accessing to state should be scaled in-out. Server with state should be updated gracefully. Elixir has all of these!
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    State should be updated in a transaction. (No shared state)

    State shold interact & isolate each other. (Application, Supervisor) Accessing to state should be scaled in-out. (GenStage, Task, Register, Erlang cluster) Server with state should be updated gracefully. (Hot code swap)
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    We can create stateful system easy, by constructing stateless parts.

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    How we can start Elixir? Let's create some applications. *

    Web application with Phoenix. * Slack bot.
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    Phoenix is a Web application framework that familiar with WebSocket.

    https://hexdocs.pm/phoenix/overview.html
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    React is available (✿ >ヮ ╹ )-♡ Let's create a

    realtime interaction ∩ (＞ ◡ ＜*)∩ ♡ https://speakerdeck.com/ne_sachirou/phoenix-livereact
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    Create a Slack bot. https://github.com/BlakeWilliams/Elixir-Slack (Easy, so no topic.)

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    Installing Elixir. asdf https://asdf-vm.com/ asdf plugin-add erlang asdf install erlang

    22.0.7 asdf plugin-add elixir asdf install elixir 1.9.1
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    Text editor? VSCode with mjmcloug.vscode-elixir works.

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    Format & lint. InnerCotton https://github.com/ne-sachirou/inner_cotton is a set of standard

    development tools. mix cotton.init mix cotton.lint --fix
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    Docker image (You need Docker :-) Fix major ver.s both

    Erlang & Elixir. docker run -it --rm nesachirou/elixir:1.9_erl22
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    Textbook & document. Official guide : https://elixir-lang.org/ Official document :

    https://hexdocs.pm/elixir/Kernel.html Online textbook : https://elixirschool.com/ja/ Textbook : https://tatsu-zine.com/books/programming-elixir-ja
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    https://speakerdeck.com/ne_sachirou/elixirwan-quan-nili-jie-sita

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    Advanced resources

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    Erlang in Anger https://ymotongpoo.github.io/erlang-in-anger/text-ja.pdf You want to read this… before

    production.
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    https://speakerdeck.com/ne_sachirou/sutetohurudeda-gui-mo- akusesufalsearusoft-realtimenagemusabawoeasynitukuru

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    https://speakerdeck.com/ne_sachirou/elixir-on-containers

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    https://speakerdeck.com/ne_sachirou/phoenix-at-scale

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    https://speakerdeck.com/ne_sachirou/ddd-data-driven-development