David Greenberg: Distributed functional programming - λC Winter Retreat 2017

David Greenberg recasts functional programming concepts to find their analogies in distributed systems.

If you’re coming to the retreat, you probably are interested in FP, if not already a full-blown user of FP and its techniques. Unfortunately, when it comes time to work on systems that scale beyond one machine, many techniques in functional programming no longer seem to be possible. For example, distributed garbage collection isn’t generally available, which makes it difficult to work with immutable data structures across multiple machines. Another issue is function composition—RPC semantics are difficult to get right, and the additional network latency incurred makes many FP design pattens unrealistic in distributed environments. In this session, we’ll recast various ideas from FP to see their analogies in distributed systems. We will discuss how monotonic functions can offer many of the benefits of pure functions. We’ll look at dependencies and causality: ways our programs express the results of one computation being the input to the next computation, and performant techniques that achieve similar results in distributed systems. We’ll also analyze distributed functional data representations. By deconstructing the things we love most about FP, we’ll see how we can preserve their essence but make them work in distributed environments. You should be familiar with pseudocode—we won’t be digging into specific languages with large amounts of code, but we will look at general ways to express these ideas. You should come eager to discuss, as we’ll learn best by sharing our thoughts and revelations as we break down FP concepts and see how they can be mapped into the distributed domain.