elixir, the hipster language

(hands-on session)

philip giuliani, daniel morandini, andrea janes

topics

this is how we will spend our/your time:

conclusion and finish the buffet!

installation

practice

time!

introduction

break!

technical/

philosophical part

people from industry arrive

elixir?

Elixir is a functional, concurrent, general-purpose programming language that runs on the Erlang virtual machine (BEAM)*.

 

Elixir builds on top of Erlang and shares the same abstractions for building distributed, fault-tolerant applications.

 

Elixir also provides a productive tooling and an extensible design.

* https://en.wikipedia.org/wiki/Elixir_(programming_language)

hipster?

so... let's start

do you use an editor?

elixir basics

  • we look into
    • chapter 2
    • chapter 13

task 1

  • open your command line
  • create a new project with "mix new helloworld"
  • open the project in your editor

task 2

  • open your command line
  • create a new project with "mix new helloworld"
  • open the project in your editor
  • let's have a look at the structure

task 3

  • in the command line, change to the project folder
  • execute "iex -S mix", this
    • compiles the project
    • runs the interactive shell
    • and loads the project into the shell so that we can test it
    • enter "Helloworld.hello"
    • you should get ":hello"

task 4

  • define a new function like this:

 

 

 

 

  • in your command line, within iex
    • run "recompile()"
    • check that there are no errors
    • run "Helloworld.sum1"
    • if you enter two integers, it works
    • what if you enter "4.2"?
    • what if you enter "abc"?
def sum1() do
  {a, _} = IO.gets("enter a: ") |> Integer.parse 
  {b, _} = IO.gets("enter b: ") |> Integer.parse
  a+b
end

task 5

  • define a new function like this:

 

 

def sum2() do
  IO.gets("enter a: ") |> Integer.parse |> handle_result    
end

def handle_result({number, "\n"}) do
  IO.puts "You entered #{number}"
end

def handle_result({_, whaaat}) do
  text = String.replace_trailing(whaaat, "\n", "") 
  IO.puts "You did not enter an integer. What is #{text}?"
end

task 5

  • in your command line, within iex
    • run "recompile()"
    • check that there are no errors
    • run "Helloworld.sum2"
    • if you enter an integer, it works
    • what if you enter "4.2"?
    • what if you enter "abc"?

task 6

  • define a new function like this:

 

 

def sum3() do
  result = IO.gets("enter a: ") |> Integer.parse
    
  case result do
    :error -> "You entered a string!"
    {a, "\n"} when a > 100 -> "You entered a number higher than 100"
    {_, "\n"} -> "OK"
    {_, _} -> "Incorrect input!"
  end
end

task 6

  • in your command line, within iex
    • run "recompile()"
    • check that there are no errors
    • run "Helloworld.sum3"
    • if you enter an integer, it works
    • what if you enter "4.2"?
    • what if you enter "abc"?

task 7

  • write a function that lets you enter two numbers and an operation character ("+" or "-")
  • output the correct result
  • use pattern matching instead of "if"

 

 

task 8

  • Read the Enum.map and Enum.filter documentation of Elixir
  • Define
  • fahrenheit_temps = [32, 68, 100, 212, 50, 75]
  • max_celsius = 30

 

Write the code to first convert to Celcius ((fahrenheit - 32) * 5 / 9) and then filter by max_celcius

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