Arrows don’t really _do_ anything. Just like monads, they’re just a generic interface and their behaviour depends entirely on the instance implementation.
You can have stream transformers that fit in de arrow class, and parallel composition might then mean that things are done concurrently. How that compares to our approach entirely depends on the exact stream transformer implementation.
Note that the ConduitT type that we use doesn’t really fit in the Arrow class, due to the additional parameter for the return type.
