functional vs objective thinking and elixir data structures are immutable

gistfile1.txt

doc = %{id: "Foo"}

#wrong
defmodule FooBar do
  def valid_version(doc) do
    if (is_integer(doc.version)), do: doc, else: doc.version = 1
  end
end

# correct
defmodule FooBar do
  def valid_version(doc) do
   if (is_integer(doc.version)), do: doc, else Map.put(doc, :version, 1)
  end
end