fs2 (reactive streaming, https://github.com/typelevel/fs2 https://github.com/typelevel/fs2) written in Scala. It shows how nicely things can compose in a typesa

fs2 (reactive streaming, https://github.com/typelevel/fs2 https://github.com/typelevel/fs2) written in Scala. It shows how nicely things can compose in a typesafe way if the language supports it. And then, the opposite is Monix (https://monix.io/ https://monix.io/) also written in Scala. It's also about reactive streaming and the API is great, but the internal code is ugly because it sacrifices readability/composability for performance.