How I learn Clojure

[tokaygekko]

Reagent

Today I have fun with reagent. I built some very simple application and it is very strange... I don't need redux, redux-dev-tools, hot-reloading tools and other things... And I can connect to my application by REPL and do everything by it. For example, we can call alert in a browser by REPL. It's strange but attractive :)

[tokaygekko]

Long vacation

I got long vacation because all my team was "fired" from project that we were developing. It's ridiculous situation, but it happens. Well, now i have a lot of time and want to spend sometime on clojure of course. Yesterday i done this article: https://ericnormand.me/guide/clojurescript-tutorial I got a lot of moments that I didn't understand. Mostly, about operations with data, for example - swap, vector, range, conj. I don't know how it works and need to know it.

[tokaygekko]

Entry threshold

I heard a lot about barriers to entry in Clojure and I didn’t understand what exactly it means. Now, I think I see what it means. The syntax is very simple and it is very easy to understand how to work with small functions. But in another hand - a lot of small functions and APIs. Well, we need to know about this heap of functions and language APIs :) What can I say here? Of course - Let’s go people! :)

[tokaygekko]

Reading 2

So, honestly, it is boring to read about data structures and data annotations like Spec or about error handling, BUT if we will try to compare this book and a book about Javascript we see the difference. In a classic book about Javascript a loooot of pages about syntax or about some species in work with data-types or other sides of language. Here is another situation. A lot of information is all about data: how to specify the data, how to annotate the data structure etc. And it inspires me! It is the most important thing in programming, and it seems this part is very elaborated in Clojure. 

[tokaygekko]

Reading

Well, the last time I read a book about Clojure. “Clojure in production” by one Russian author. I have known about Spec and the basics of exceptions in Clojure and Java world. Wuhhhh... it seems complicated for me now, but I know that it is just the first time. I want to read this book to know all the essential things in practice.

[tokaygekko]

Api summarise

So, as summarise my today experiment with API writing I see a few points: 1. It is the fastest way to build API from scratch compared with Ruby on Rails, Node.js, or PHP frameworks. 2. It has dynamic types and we need to watch of data types what are we working with. Of course, we have a way to use static typing, but I don’t want to overhead it 3. It is the most pleasure technology that I have worked with.

[tokaygekko]

Api refactoring

I have refactored my first Clojure api. It was very easy to understand. I just separated core, routes and handlers in namespaces (clj-files) and connect them by :require, and that’s it.  https://github.com/tokaygekko/clj-todo-rest

[tokaygekko]

Data types

A few minutes ago I tried to filter the vector or list, doesn’t matter, by the filter function. I spent about 15 minutes understanding that I tried to compare different data types - String and Number. Of course, I couldn’t find it out by repl or logs because there is no info about data types. So, be careful with data types in Clojure :)

[tokaygekko]

First Clojure rest app

I got a great article about simple example of routing and api with Clojure https://otee.dev/2022/01/25/clojure-backend-using-ring-jetty-compojure.html

[tokaygekko]

Todo rest api

Today I started to write my study REST api for todo list app. Hahaha... I thought like “Alright... I will be trying to do it for an hour, and of course I will get a lot of problems and something will not work of course, but OK, i will handle it later”. BUT, I had done it after 1 hour! It was amazingly simple! Yes, now I need to write some logic for add todo and remove it from a local variable, but it is very simple to understand and do. Answers to every question I got in the documentation. And IT’S JUST SIMPLE WORKS! Goddamn... I’ve really never had so predictable and easy-to-understand development. Here is my repo if it is interesting - https://github.com/tokaygekko/clj-todo-rest

[tokaygekko]

Clojure in development

Today I found a great book about Clojure. The author didn’t write about syntax, basic principles of application, client-server architecture, and other beginner stuff, he skipped it. He wrote about examples from practice and this is absolutely amazing. I have never read so simple explanation of HTTP. Goddamn, why I have not got it before... Because I didn’t know about Clojure :) I have noticed one more time that may be functional programming really changes the mind. Unfortunately, this book uses the Russian language, but I know the English version will be done soon.  https://grishaev.me/clojure-in-prod/  I want to say thank you to Ivan Grishaev! You are awesome!

[tokaygekko]

Lein and Main

Well, I spent a little time and have researched the next thing. We can use any function like main-function for our project if set `:main` key in `defproject`. After that, if we run `lein start` it starts the function that we set in `defproject`.

[tokaygekko]

Dependencies

For projects from scratch, we can use deps.edn file for dependencies description, but if you use Leiningen and create project by lein CLI tool you must have a project.clj file and you can store information about dependencies in this file in the block :dependencies

[tokaygekko]

Some thoughts

I thought about my Clojure experiments for the last time, and it looks very attractive. As I understood, finally we get a lot of small predictable pure functions and connect them. Sometimes we connect them in function with side-effects, it doesn’t matter at all if we get just one or two functions with a side effect. It still looks reliably. One more thing that I was amazed by it is how easy it looks. Insanely easy. Of course, I have many questions about debugging, but it just needs some time. I will get it for sure. 

[tokaygekko]

Clojure cheatsheet

Today I found a cheatsheet about basic Clojure operators, constructions e.t.c Here it is - https://github.com/metosin/sauna-todo/blob/master/src/clj/intro/basics.clj

[tokaygekko]

Alleluia!

As I have known, Intellij IDEA has a free version! And I have got it today’s morning. Yes, it works! I didn’t wait and made a website with static pages and web-server by this manual - https://nickgeorge.net/programming/custom-static-clojure-websites-an-update/ So, such a simple thing! I’m amazed by this. It is very clear and simple for understanding. Just one moment confused me - how to change a web-server port. I changed it by adding a port to the command lein ring server 4000 and it works. How it is simple! 

[tokaygekko]

I got stuck

My license for intellij idea has expired and I can’t buy a new one because my credit card is blocked. It’s blocked because of sanctions. My current credit card opened in a Russian bank. So, I don’t want to research any other editor again and I’ll get a pause until I get a new bank account with working credit card. Well, see ya soon!