Formatting a function definition with long pattern matching/guard clauses.

long_pattern_match.ex

# A message is supposed to come in like this but we don't know if the fields are filled out.
message = %{
  route: %{
    destination: "Tim",
    source: "Paul"
  },
  type: :friend_request,
  payload: %{
    size: 32,
    content: %{
      message: "I'd like to be your friend."
    }
  }
}

# Use pattern matching/guard clauses to verify it at least has a target and a message.
def handle_friend_request (
  %{route: %{destination: target}, type: :friend_request, payload: %{content: %{message: message}}}
) when is_binary(target) and is_binary(message) do
  # Write some code here.
end