Some years back I wrote the essay “Functional programming, meet OOP”. A few months ago I gave a talk loosely based on it but with some major improvements. It didn’t feel right to update the original post so instead I decided to rewrite it to go a little bit more in detail of the higher level concepts and to make it less Clojure-specific.

In my post Implementing numbers in “pure” Ruby I established some ground rules that allowed us to use some basic ruby stuff like equality operator, booleans, nil, blocks and so on.

But what if we had absolutely nothing, even basic operators like if and while? Get ready for some pure OOP-madness.

Originally posted on medium.com

I enjoy experimenting with programming paradigms and trying out some interesting (to me) ideas (some things become posts, like this and that). Recently I decided to see if I can write object-oriented code in a functional language.

Originaly posted in carwow blog on medium.com

Object-Oriented Programming to me means that the system is divided into objects. An object is just an entity that has some state and some behaviour. You can make your object do something by sending it a message, hoping that it will understand you.

For practical reasons, every language has some primitives; basic data types you can use to write your program. Even though Ruby is, supposedly, a pure OO language (everything is an object), it has some primitives nevertheless.

For instance, numbers. They look like objects, they have methods and stuff. However, what are they really? 2 and 3 are different instances of the Integer class, so they are supposed to have a different state. But what is that state? Magic.

Let’s try and implement numbers on our own, without magic. Just for fun.