Functional architecture - The pits of success - Mark Seemann

I spend a lot of time thinking about these sorts of topics (actually, I just taught a 4 hour session yesterday that used most of the terms in this article), working with newer, less experienced developers, and trying to figure how to distill the essence of "architecture" down to something simple that everyone can start with. This is what I’ve started telling people: Use mostly functions, try to make most of them pure. I think that can get people (even new devs) 80% of the benefits (testability, composability, loose coupling, and the ability to reason about code) of more complicated, prescriptive architectures (Hexagonal, Onion, Ports & Adapters, Clean, etc) with a minimal amount of ramp up. Of course, this isn't the solution to every problem (it obviously depends on the domain you are working in, for me its webDev and backends), but I think maybe its a good way for people to start. Edit: Here is a great talk demonstrating that by following a simple functional approach, your code can naturally fall into a “pit of success”: [this video]

The goal is that everything in the core is pure data types and functions. Now, depending on your problem domain, your core can be small or huge compared to the shell. Your question was all about IO/effects. They are impure and belong to the shell. If what you work on does mostly IO then you will have a lot of impure code lying around by definition. Still, the idea is that you should keep the amount of time spent in impure land minimal, ie. drop into pure structures/computation as soon as possible during program execution and only dip out of on occasions when you have to do IO. Here is a good talk about these ideas: [this video]

> So while FP is just another tool, it's also a framework for thinking that helps people make better choices I’ve been getting more into functional programming this past year (via Clojure, though my day-job is mostly JavaScript/TypeScript) and this is the big takeaway for me. Type theory and monads may have their place, but thinking about separating logic from side-effects is, I think, the most valuable aspect of functional programming. That is a thought process that you can apply in pretty much any language that will give you the biggest bang for your buck. Edit: Here’s some great examples of the benefits of functional thinking without going off the deep end. 1. Boundaries by Gary Bernhardt - [link] 2. Pits of Success by Mark Seemann - [this video] 3. Grokking Simplicity by Eric Normand - [link]

5yrs ago I was roughly the same, depends how much you commit up front. I had minimal FP experience, so I bought "Domain Modeling Made Functional" [1] by Scott Wlaschin and used it for side projects / class libs first. Took about 6 months to experience the full mental shift. Even if you eventually decide you can't commit a team to F#, it's highly worth it because doing at least one app in F# will vastly improve your C# and how you structure applications. [2] I personally just got addicted to the expressive power, it's hard to replicate with any other ecosystem given the full power of .NET under the hood. Giraffe is also a great place to start if you know ASP.NET Core. [3] [1] [link] [2] [this video] [3] [link]