Elixir Programming Examples

Elixir Typespecs Custom Types

elixir

defmodule FunnyCalculator do
  @type number_with_joke :: {number, String.t}

  @spec add(number, number) :: number_with_joke
  def add(x, y), do: {x + y, "You need a calculator to do that?"}

  @spec multiply(number, number) :: number_with_joke
  def multiply(x, y), do: {x * y, "It is like addition on steroids."}
end

{result, comment} = FunnyCalculator.add(10, 20)
IO.puts(result)
IO.puts(comment)

Elixir Comprehensions into Option

elixir

IO.puts(for <<c <- " hello world ">>, c != ?\s, into: "", do: <<c>>)

Elixir Sigils Word Lists

elixir

new_word_list = ~w(foo bar bat)
IO.puts(new_word_list)

Elixir Sigils Char Lists

elixir

new_char_list = ~c(this is a char list containing 'single quotes')
IO.puts(new_char_list)

Elixir Sigils Regex

elixir

# A regular expression that matches strings which contain "foo" or "bar":
regex = ~r/foo|bar/
IO.puts("foo" =~ regex)
IO.puts("baz" =~ regex)

Elixir Processes Message Passing

elixir

send(self(), {:hello, "Hi people"})

receive do
   {:hello, msg} -> IO.puts(msg)
   {:another_case, msg} -> IO.puts("This one won't match!")
end

Elixir File IO Path Module

elixir

IO.puts(Path.join("foo", "bar"))

Elixir Protocols

elixir

#Defining the protocol
defprotocol Blank do
   def blank?(data)
end

#Implementing the protocol for lists
defimpl Blank, for: List do
   def blank?([]), do: true
   def blank?(_), do: false
end

#Implementing the protocol for strings
defimpl Blank, for: BitString do
   def blank?(""), do: true
   def blank?(_), do: false
end

#Implementing the protocol for maps
defimpl Blank, for: Map do
   def blank?(map), do: map_size(map) == 0
end

IO.puts(Blank.blank? [])
IO.puts(Blank.blank? [:true, "Hello"])
IO.puts(Blank.blank? "")
IO.puts(Blank.blank? "Hi")

Elixir Streams

elixir

odd? = &(rem(&1, 2) != 0)
res = 1..100_000 |> Stream.map(&(&1 * 3)) |> Stream.filter(odd?) |> Enum.sum
IO.puts(res)

Elixir Enumerables Reduce without Accumulator

elixir

res = Enum.reduce([1, 2, 3, 4], fn(x, accum) -> x + accum end)
IO.puts(res)

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