Yet another validation DSL

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.

ruby -run

This is a loose translation of my post from 2017

Recently, I was looking for a one-liner to start a web-server in the current directory. Stack Overflow gave me this command:

ruby -run -e httpd -- -p 9090 [DIR]

So what is this mysterious -run option an why is it not in the ruby manual?

ruby -e for better console experience

This is a loose translation of my post from 2017.

Ruby was influenced by Perl and can substitute it in its niche of “practical extraction and reporting”. In this small post, I’ll talk about using ruby for simple text processing in the terminal.

I hate Ruby constants

This is a loose translation of my post from 2018.

Ruby is a very complex programming language. It’s incredibly beautiful and expressive. However, it also has lots of traits and implementation details that even some of the experienced Ruby programmers may not know. One of these is constant lookup.

I’m not gonna try to explain the lookup algorithm works. I just want to raise some awareness of the topic. Mostly, it’s just a rant.

Programming only with classes

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.

Writing a small web service with Ruby, Rack, and functional programming

Originally posted on

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 ;)

Implementing numbers in "pure" Ruby

Originaly posted in carwow blog on

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.