This is why I recently tried Clojure

This is why I recently tried Clojure

I am coming from a mixed software development background. Starting with, when I was a child, over to Java for a long time, ending with Ruby, Javascript / Typescript.

On my whole journey, I did not get in touch with functional programming a lot. I furthermore did not spend a lot of my years with declarative programming. That's something I have been up to for the past few years.

Difference between imperative and declarative

const arr = [1, 2, 3, 4, 5];

// imperative
let itemsArr = [];
for (const item of arr) {

// declarative
let itemsArr = => `Item-#${item}`);

What is Clojure anyways?

It's a Lisp-like functional programming language. It runs on top of the Java Virtual Machine. Key features include:

  • all variables are immutable by default. You can use so-called atoms to get the chance to manipulate variables

  • "It's just data" is a key concept that for example also states: even function calls are just a list. The first element of the list is the function name, followed by the parameters

  • Concurrency in mind.

What does it look like?

(def arr [1, 2, 3, 4, 5])

(map #(str "Item-#" %1) arr) ;; Same example as in javascript

Why did I do this to me?

Good question. I still haven't found a good answer to that one. I was heavily interested in whole new paradigms, that are outside of my horizons:

  • declarative programming (correct use of reduce, map, etc.)

  • functional programming (bye, bye let. Hello const)

I have furthermore seen an amazingly funny presentation about Clojure.

Who is using Clojure A Brazilian bank runs fully on Clojure microservices. They state they have over 1000 microservices in use.

Was it worth it?

Somehow, yes. It taught me new ways to approach a problem and showed me, how f*cked I am once possible solutions get a new requirement: immutability.


Would I recommend getting your head around Clojure? Well if you have some spare time and want to learn a new language, then it has served me well.

I highly recommend you, to watch the talk mentioned above.