A scenario that made the need for 'with' clear to me: You have a function that passes a subject through several functions using the pipe: subject |> fn1 |> fn

A scenario that made the need for 'with' clear to me: You have a function that passes a subject through several functions using the pipe: subject |> fn1 |> fn2 |> fn3 But now you want to return an error monad if everything went wrong. You could do the following: with {:ok, v1} <- f1(subject), {:ok, v2} <- f2(v1), do: f3(v2)