簡介 Elixir & Phoenix

1. Elixir
A dynamic, functional language designed for
building scalable and maintainable applications.
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2. Elixir ‑ taiansu
elixir or ‑
Hype Driven Development ‑ Marek Kirejczyk
React, TDD is dead, Microservice, NoSQL, Elixir/Phoenix
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3. Intro
José Valim (@josevalim)
Rails Core Team since early 2010
v1.0.0 ‑ Sep 10, 2014
Erlang Virtual Machine (BEAM)
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4. Erlang (1987‑)
Erlang Virtual Machine (BEAM)
1. lightweight process
2. supervisor tree ‑ fail fast, let it crash
3. Hot swapping
IM/
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5. Toolchain
nodejs Elixir
package manager npm hex.pm
CLI npm mix
REPL node iex
test jest, mocha... ExUnit (doctest)
docs JSDoc ExDoc
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6. Types
Value types Collection types
Arbittrary‑sized integers Tuples
Floating‑point numbers Lists
Atoms Maps
Ranges Binaries
Regular expressions
number < atom < tuple < map < list < binary
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7. Immutability
‑ All values are Immutable
‑ Copying Data
iex> list1 = [3, 2, 1]
[3, 2, 1]
iex> list2 = [4 | list1]
[4, 3, 2, 1]
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8. Pattern Matching (1/2)
Not an assignment
iex> a = 1
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iex> 1 = a
1
iex> 2 = a
** (MatchError) no match of right hand side value: 1
More Complex Matches
iex> list = [1, 2, 3]
[1, 2, 3]
iex> [a, 2, b] = list
[1, 2, 3]
iex> a
1
iex> b
3
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9. Pattern Matching (2/2)
Variable Bind Once (per Match)
iex> [a, a] = [1, 1]
[1, 1]
iex> a
1
iex> [b, b] = [1, 2]
** (MatchError) no match of right hand side value: [1, 2]
pin operator: ^
iex> a = 8
8
iex> [^a, 2] = [1, 2]
** (MatchError) no match of right hand side value: [1, 2]
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10. Anonymous Functions
iex> sum = fn (a, b) ‐> a + b end
iex> sum.(1, 2)
3
iex> swap = fn {a, b} ‐> {b, a} end
iex> swap.({6, 8})
{8, 6}
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11. Modules and Named Functions (1/2)
Function Calls and Pattern Matching
defmodule Factorial do
def of(0), do: 1
def of(n), do: n * of(n ‐ 1)
end
Guard Clauses
defmodule Factorial do
def of(0), do: 1
def of(n) when n > 0 and is_integer(n) do
n * of(n ‐ 1)
end
end
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12. Modules and Named Functions (2/2)
Default Parameters
defmodule Example do
def func(p1, p2 2) do
IO.inspect [p1, p2]
end
end
Private Functions
defmodule Factorial do
defp foo(a): do: false
end
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13. Pipe Operator |>
people = DB.find_customers
orders = Orders.for_customers(people)
tax = sales_tax(orders, 2017)
tax = DB.find_customers
|> Orders.for_customers
|> sales_tax(2017)
tax = sales_tax(Orders.for_customers(DB.find_customers), 2017)
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14. Heads & Tails
iex> [head|tail] = [1, 2, 3]
[1, 2, 3]
iex> head
1
iex> tail
[2, 3]
defmodule MyList do
def len([]), do: 0
def len([head|tail]), do: 1 + len(tail)
end
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15. Concurrency
current_process = self()
# Spawn an Elixir process (not an operating system one!)
spawn_link(fn ‐>
send current_process, {:msg, "hello world"}
end)
# Block until the message is received
receive do
{:msg, contents} ‐> IO.puts contents
end
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16. Take Away
Erlang
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17. Reference
Tutorial
Try Elixir ‑ Code School
elixir‑koans
Site
elixir‑lang
hex.pm
Elixir Taiwan (FB group)
NewsLetter
Elixir Radar
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18. Part 2
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19. Phoenix
A productive web framework that does not compromise speed
and maintainability.
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20. Intro
Chris McCord (@chris_mccord)
v1.0.0 ‑ Aug 28, 2015
server‑side MVC pattern, like Rails / Django
high developer productivity and high application performance
channels for implementing realtime features
Final results from Phoenix channel benchmarks on
40core/128gb box. 2 million clients, limited by ulimit
‑ Tweet from @chris_mccord
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21. Analogies
nodejs Rails Phoenix
minimal express Rack Plug
ORM/ODM Mongoose ActiveRecord, Mongoid Ecto
Template .ejs, .jade .erb .eex
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22. Phoenix
The Endpoint
The Router
Controllers
Views
Templates
Channels
PubSub
http://www.phoenixframework.org/docs/overview
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23. Plug
defmodule HelloPhoenix.MessageController do
use HelloPhoenix.Web, :controller
plug :authenticate
plug :find_message
plug :authorize_message
def show(conn, params) do
render conn, :show, page: find_message(params["id"])
end
defp authenticate(conn), do: ...
defp find_message(id), do: ...
defp authorize_message(conn, _), do: ...
end
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24. Ecto
supports PostgreSQL, MySQL, MSSQL, SQLite3 and MongoDB
Repo
Schema
Query
Changeset
def index(conn, _params) do
users = Repo.all(User)
render(conn, "index.html", users: users)
end
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25. Take Away
Rails
Elixir syntax ( )
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26. Reference
Site
Phoenix Framework
Brunch.io
Course
The Complete Elixir and Phoenix Bootcamp ‑ udemy
Book
Programming Phoenix
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27. Q & A
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