Changed all are in the actual project

changes.exs

def decrement(%Monad.Result{type: :ok} = state) do
    state.value
    |> decrement
end
def increment(
    %Monad.Result{type: :ok} = first,
    %Monad.Result{type: :ok} = second ) do
      second = second.value |> Enum.count
      increment(first.value, second)
end
def combine(
    %Monad.Result{type: :ok} = first,
    %Monad.Result{type: :ok} = second ) do
      combine(first.value, second.value)
end
def filter(%Monad.Result{type: :ok} = list), do: list.value |> filter()
def sum_of(%Monad.Result{type: :ok} = list), do: list.value |> sum_of