Intro

I’ve switched from Ruby and Clojure for my personal stuff to Common Lisp a couple of years ago. I think it fits my programming style very well. But it’s a very strange language.

CL has a lot of stuff in it. It feels like it tried to cater to many different types of programmers all at once. It mixes functional, procedural, and object-oriented ideas. It makes use of dynamic binding (which isn’t very common nowadays) whilst being mainly lexically scoped and supporting closures.

However, some things in CL don’t seem practical at all. Or maybe just weird. In this essay I’m going to show some things I’m weirded out by.

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.

Recently I’ve been working on a personal project (a Tinder bot integrated with ChatGPT and using Telegram Bot API as UI). I started out with a small prototype in Ruby (like 40 lines script) however then I switched to Common Lisp.

The reason for it was that I wanted to use the language for a while but couldn’t bring myself to (because I hate LISP-2 and I also thought and still do that CL is a language equivalent of a dumpster).

My opinion of the language hasn’t changed but I did love the experience. And now I’m gonna try to explain why.

I’ve been reading my old essays and found this one written in Russian back in 2019.

Essentially, it describes a Ruby gem (library) I had written that allows you to create your own validation DSL as a bunch of functions and data. It emphises simplicity and flexibility. I thought it had a really interesting idea behind it so I’m going to rehash it here.

The below can be applied to any language (admittedly, it’ll be less convenient in some). I wrote examples in Ruby and Clojure.

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.

Some time ago I was doing some small introductions to basic algorithms I learned back in school to my colleagues at carwow (just for fun). Some of them became posts on medium.

After one of them a colleague told me about sleep sort algorithm. I think it’s ingenious and should be in my blog.

Inspired by Implementing numbers in “pure” Ruby

When I started working with Elm programming language I was amazed how simple and yet powerful the type system is. It’s just shocking how far you can go with with just having some symbols and type constructors.

But how really far can we go? Well, I decided to test it out starting with implementing integers and expressions with them. I decided to use Haskell for that. Its laziness may be useful.

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.

Originally posted on medium.com

I love Ruby. I also love object-oriented programming. However, nowadays functional programming is getting more and more attention. And that’s not surprising because the functional paradigm has a lot of advantages.

Ruby, being a multi-paradigm language, allows us to write programs in a functional style. Let’s see if we can write a web application this way. Maybe we even end up inventing a web framework ;)

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.