Modules and Named Functions

factorial1.exs

defmodule Factorial do
  def of(0), do: 1
  def of(n), do: n * of(n-1)
end

factorial2.exs

defmodule Factorial do
  def of(0), do: 1
  def of(n) when n > 0 do
    n * of(n-1)
  end
end

guess.exs

defmodule Chop do

  def guess(actual, low..high) do
    currently_guessed = div(low+high, 2)
    IO.puts "Is it #{currently_guessed}"
    try(actual, currently_guessed, low..high)
  end

  defp try(actual, currently_guessed, _) when actual == currently_guessed do
    IO.puts(currently_guessed)
  end

  defp try(actual, currently_guessed, _low..high) when actual > currently_guessed do
    guess(actual, currently_guessed+1..high)
  end

  defp try(actual, currently_guessed, low.._high) when actual < currently_guessed do
    guess(actual, low..currently_guessed-1)
  end

end

pipe_operator.exs

people = DB.find_customers
orders = Orders.for_customers(people)
tax    = sales_tax(orders, 2016)
filing = prepare_filing(tax)

filing = DB.find_customers
           |> Orders.for_customers
           |> sales_tax(2016)
           |> prepare_filing