Functional streams are a vital tool in any ecosystem. They can simplify the code for webservers, event loops, and data-intensive applications. But they are notoriously difficult to understand. In this talk, we'll explore a mental model of stream execution in fs2, a functional stream processing library in Scala. We'll use our model to draw simple diagrams for complex streaming scenarios, and see how these diagrams can be generated automatically using the aquascape library. Finally, we'll bring our model to the masses. We'll use Scala.js to create interactive, browser-based diagrams that can be integrated into fs2's online documentation. By the end, we'll have a solid understanding of functional streams. With aquascape, you'll see that streams are not only easy to read, but easy to reason with too.

We’ll navigate the rich waters of streaming using fs2, exploring how streams underpin a wide range of Scala applications—from event-based systems to time-based concurrency challenges. We’ll learn what streams are for, when to use them, and how to put a streaming framework to work in your codebase.