The Futures are Calling and I Must Choos...

Scala has a Future type in the standard library, but when we use other libraries we have competing abstractions: Scala Futures, Twitter Futures, Java CompletableFutures, Guava ListenableFutures. Other libraries like Scalaz, Monix, and FS2 bring us Task abstractions, which are similar to Futures but lazily executed. How do all these variants relate to one another? When should we use one over another? How do we interoperate when we have to deal with code that uses a different variant? Starting from the basics of Scala Futures, we'll build up an understanding of how to select the best one for a codebase, how to make them work together, and some of the pitfalls. Along the way we'll even see some other tricks for making these useful abstractions when combined with other effects.