Elixir/Phoenix TODO list application

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# Elixir/Phoenix workshop

---
# Goal

To bulid a simple TODO list web application with Elixir and Phoenix

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# Elixir

Key language features
* Python-like syntax
* Functional programming
  * Everything is an expression
  * Few side-effects
* Dynamic typing
* Pattern matching
* Meta programming

Built on top of Erlang
* Compiles to Erlang byte-code (BEAM) and runs on the Erlang virtual machine
* Can use the Erlang standard library as well as third-party Erlang libraries/packages

Erlang
* General-purpose functional programming language
* Developed by Ericsson
* Focus on: Concurrency, fault tolerance, high availability, hot swapping, real-time computing

---
# Example

```elixir
defmodule Hello do
  def hello() do
    IO.puts("Hello World!")
  end
end

Hello.hello()
```

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# Running an Elixir program

REPL 
```sh
iex
```

Running a script file
```sh
elixir program.exs
```

Running an application
```sh
mix run
```

Running a Phoenix application
```sh
mix phx.server
```

Connect to a running application
```sh
iex -S mix
```

Running in production is a different story...

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# Phoenix

* Phoenix is a framework for developing web applications with Elixir
* Phoenix is based on the model-view-controller (MVC) methodology
* HTML is generated on the server and sent to the client
* Not much JavaScript

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# Setting up a new Phoenix app

Phoenix provides a helper command which will generate the basic directory and file structure needed by a Phoenix app:
```sh
mix phx.new
```

For this project I created the directory with a Git repository in advance so I had to use a slightly more complicated command:
```sh
mix phx.new . --module ElixirTodoWorkshop --app elixir_todo_workshop
```

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# Running Phoenix

Use this command to start the Phoenix application you just created:
```
mix phx.server
```

Now you can visit the application at http://localhost:4000/:

.center[<img src="images/phoenix-default-index.png" title="Phoenix default index page" width="350">]

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# TODO list application
Will consist of two entities:

![TODO list application](images/todo-list-entities.png?raw=true "TODO list application")

Phoenix also provide helper commands to generate the DB schema, models, controllers, views and HTML templates for these entities:
```sh
mix phx.gen.html Todo List lists name:string
```

```sh
mix phx.gen.html Todo Item items description:string
```

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# Elixir tooling

* Mix: Elixir build tool
* Rebar: Erlang build tool
* Hex: Elixir/Erlang package manager (https://hex.pm/)
* Distillery: Release build tool for Elixir
* Edeliver: Deployment tool for Elixir and Erlang

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# The end

## Questions?