The article, co-authored by Tyler Sullberg and Musa Barighzaai, discusses the challenges and nuances of using Clojure as a backend language at CircleCI, a company experiencing growth. Unlike the widely-used JavaScript, Clojure is less familiar to many developers, yet offers a unique functional programming style that emphasizes immutability and dynamic types. The article outlines the differences between Clojure and JavaScript, noting that while JavaScript allows for mutable objects and extensive use of object-oriented patterns, Clojure promotes immutable data structures and a functional approach. Clojure’s design revolves around simplifying data manipulation, and it operates on the JVM, granting access to Java libraries. The text emphasizes the importance of understanding these differences, as they impact how developers should approach building microservices in Clojure. The article is the first in a series aimed at guiding developers through setting up Clojure microservices, using JavaScript as a comparative reference, and highlights the benefits of Clojure’s REPL-driven development workflow.