Kelsey Gilmore-Innis


Recorded at Domain-Driven Design 2016, January 26-29, Brussels


Kelsey is the Director of Technology at Sexual Health Innovations, creating technology that advances sexual health and wellbeing in the United States. SHI is currently building Callisto ( to provide a more empowering, transparent, and confidential reporting experience for college sexual assault survivors. Kelsey co-founded the Lambda Ladies group for women in functional programming ( and speaks regularly around the world on technical topics. Outside of SHI, Kelsey pursues the study of baseball, R&B, presidential trivia and other all-American pursuits.

Talk: Enjoy Yourself Because You Can't Change Anything Anyway: Immutable Data in the Real World

Concurrency: it’s way easier when values don’t change. True fact! But what else can we gain from making our data immutable? Let’s look at the benefits and tradeoffs--beyond concurrency--of applying the concept of immutability to real world programs. We'll start by looking at the history of immutability in programming, both in the object-oriented and functional paradigms, and examine ways it can reduce our cognitive burden and improve readability. We'll discuss some elegant and counter-intuitive outcomes of functional data structures that take advantage of immutable data. With those in mind, we’ll take a hard look at the performance of implementations of immutable collections in real-world programming languages. Finally, we'll explore frameworks do exciting things with immutable data, from the database level (append-only DBs) to data processing (Samza) to front-end development (Facebook’s React & Om).