The Scala community has been interested in representing asynchronous computations through the type system for a long time. While Scala provides you with a well-supported Future implementation, both the Typelevel and Scalaz communities are working towards their own implementation of an IO. This leads to a lot of friendly competition between these libraries, leading to major improvements of their performance. This talk will present the current options available to build programs and manage effects in the type system, their difference from a developer perspective, their usage in the wider community, and how one can decide which implementation to use.