Unit is not inferred as INothing

[Fristi]

I have a Pipe[F, Byte, Unit] but this is not inferred as Pipe[F, Byte, INothing] ? I assume that's the case, is there a combinator for this cast?

[mpilquist]

Use the .drain method on Stream to discard those units. For example:

val p: Pipe[F, Byte, Unit] = ???
val q: Pipe[F, Byte, Nothing] = p.andThen(_.drain)

That discarding has to be manual. To see why, consider this program:

val s: Stream[Pure, Unit] = Stream(1, 2, 3).as(())
val s2: Stream[Pure, Int] = Stream(4, 5, 6)
val s3 = s ++ s2

What's the type of s3 here? It's a Stream[Pure, AnyVal] because AnyVal is the least upper bound of Unit and Int.

[Fristi]

That works! Thanks!