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
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.)