Ian Thomas - From Zero to Live with Functional JavaScript Applications (Part 1) - λC 2018

We are here, speakers and delegates alike, because we believe (or at least have a hunch) that developing software using functional programming principles will lead to better products, systems, and developer experiences. But isn't it surprising how often we find ourselves evangelising the benefits of FP only to find external factors and delivery pressures blocking our way?

Hear how we navigated the choppy waters of internal politics and non-functional constraints to help refactor our products into our vision of programming perfection. Leave with new ideas on how you can spread the passion for FP and identify opportunities to use your skills to drive value for your customers and business.

This talk is based on my personal experience with this situation while working for one of the few UK tech companies based in the north of England and valued over £1bn. Like many companies, we've been through various phases of growth, all building on a monolithic OOP codebase:
- The outsourced phase.
- The early, in-house phase (we're small, agile and, rapidly delivering features).
- The awkward scaling, misshapen, and unstable phase (the rough edges of early decisions are coming back to haunt us).
- The fear cycle phase (small changes cause bugs and outages so the scope of changes decreases, leading to more technical debt, bugs, and slower delivery).

However, we've seen the benefits of using functional programming. Multi-million-pound opportunities have been realized through composable, functional JavaScript. Our bug count has decreased and speed to market has improved. Yet, despite this success, we're still fighting to stop people using mutable state, leaky abstractions ("classitis""), and code so full of side effects you can't write a test without first having to mock the majority of the application. Scaling teams and the software they produce is hard!