Ep 045: Why Have Derived Fields in Data When I Can Just Calculate Derived Data as Needed With a Function?

Functional Design in Clojure

Each week, we answer a different question about Clojure and functional programming.

If you have a question you'd like us to discuss, tweet @clojuredesign, send an email to [e-mail], or join the #clojuredesign-podcast channel on the Clojurians Slack.

This week, the question is: "Why have derived fields in data when I can just calculate derived data as needed with a function?" We take a focused look at the balance of using functions or derived fields and where each is preferable.

Selected quotes:

• "Clojure has a gravity toward using the built-in data structures."
• "Immutability helps you handle concurrent updates to dependent fields without using locks."
• "If you add derived fields, you can query the data using information at different levels of abstraction."