As DoorDash transitioned from Python monolith to Kotlin microservices, our engineering team was presented with a lot of opportunities to improve operational excellence and continue our obsession with reliability. While there are many ways we can improve our engineering metrics via optimized hardware and suitable system designs, one direct lever we can pull as developers to contribute to the overall engineering excellence is to write better and cleaner code on a daily basis.
And one way for developers to write cleaner code is to adopt the paradigm of functional programming (FP) using Kotlin. As a multi-paradigm general-purpose programming language, Kotlin provides a lot of the necessary toolkits we need to leverage FP in our day-to-day coding.
In this post, we are going to talk about what functional programming is, what the benefits and potential downsides of it are, how it compares to the alternative paradigm imperative programming (IP), what Kotlin provides for developers to leverage FP, and examples of how we at DoorDash write FP-style code in Kotlin.