Atom

Goodbye, Chlorine. And welcome, Lazuli!

So, if you’re not familiar with Chlorine, or any of my tooling, let me get you a refresher. If you don’t want to read it all, the TL;DR; is – Chlorine is a Socket REPL plug-in for the Clojure, and ClojureScript languages. It also supports nREPL, although to a lesser extend, and it works on the Atom editor. It also contains a VSCode version called Clover, and I tried to port it to NeoVIM and I called it Clematis.

And now, it’s gone.

For historical reasons, I wanted to rename the project for a while – so that Chlorine would stay as a “socket REPL for the Atom editor” and the new plug-in would be the “Chlorine:Next” or something like this. I tried to like the name Alya, but in the end I never did…

… and then, I stopped working with Clojure. Like, at all. For a while I haven’t touched a single line of Clojure code, although I still use ClojureScript on my personal plug-ins. But ClojureScript have a weird problem – I can’t develop two plug-ins written in ClojureScript at the same time, so I need to compile everything, except for one, plug-in for “release”. Which is annoying to say the least, so that’s why I started the “Star Ring” metapackage – to make all plug-ins a “single, unified codebase”. Unfortunately, this have its own fractal of problems that I won’t discuss now.

So not that I’m now working with Ruby, I needed better tooling for Ruby otherwise I would go crazy. Leaving the “REPL-Driven Development” of Clojure behind is a nightmare, because it’s such a great tool and it somehow “grows” in you in such a way that you can’t imagine working in a codebase when you can’t evaluate your code all the time. And that’s where Lazuli appears… but again, because of the problems with not being able to develop Lazuli and Chlorine at the same time, Chlorine’s development stalled… and I decided to stop working on it to work in Lazuli.
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By Maurício Szabo, ago

A sun sets, a pulsar is born

Recently Microsoft announced that the destruction of the Atom editor – I already posted about that, but I want to say that the community response for the sunset was really wonderful – in the beginning, I really thought that the Atom editor would die with the Microsoft announcement. But after posting on a lot of channels, and a very organized “call for arms”, we were able to organize ourselves and create something wonderful – the atom-community is now more active than ever, and indeed there is work being done right now.

People decided join our discord servers; we are reimplementing the API that will be discarded by Microsoft, and modernizing the editor like, for example, bumping tree-sitter and Electron (we now can run Atom on Electron 12); we also will need to rebrand it, and the name chose – Pulsar – could not be more fitting: it’s easy to remember, it basically means a “star that dies, but starts to spin faster and give bursts of radiation”.

I also was able to somehow bootstrap the editor without the original “bootstrap script” from Atom (that is famous to not work correctly, and also need an older version of Node.JS). I was also able to build binaries of Atom with “electron builder” – it’s library from the electron community to build the binaries instead of the way Atom do today (that is a bunch of scripts).

So this makes 5000 lines of code less that we have to keep of Electron scripts – except for the fact that there’s actually a lot of things in Atom that depends on things that these 5k lines do – like some plug-ins that misbehave when you don’t run the scripts, and all the test code that currently will not even run if you don’t bootstrap things.

So what this means for the Saturn editor? Is it the death of the product, like, will Pulsar will be basically the editor that I want to have? And unfortunately, it seems the answer for that question is “no”.
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By Maurício Szabo, ago

Killing Atom

So, Microsoft blogger decided to post about “sunsetting Atom”.

Honestly it’s an amazing euphemism for “for killing Atom” so I’m not going to bother to sweet-coat anything: in fact this post will probably have some harsh words, so if you like Microsoft (for some reason) I advise you to stop reading…

Anyway: Microsoft is a shitty piece of crap company. They committed so many crimes and the reason why they didn’t answer for most of these is because they bought the lawyers that were accusing them. When they they posted that they are going to Sunset Atom, it sounded like an inevitable thing – Atom was stalled, so they’re going to archive the repositories and if someone wants to keep using this just fork it and keep developing the editor.

But the truth is – not even this is possible. And we’re going to find out why in a moment, but first a little bit of story:

Even though Microsoft told everybody that they were going to keep developing the editor, it is strange that years later they decided to just give up on the idea. But this decision was not rushed in any way – they were planning to do that for a long time!
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By Maurício Szabo, ago

The impossibility to maintain Atom

Atom Editor was, and still is, an amazing piece of technology. It was the first practical example of web technologies running locally, applied to a really hard problem: text editors. It it was, and still is, darn good at handling code.

But it’s hard, close to impossible, to maintain as the way it is. I want you to take all my opinions with a grain of salt, because these represent my own ideas and feelings on the project – I’m not a full-time Atom developer, nor I intend to be one. I just closely followed its development cycle, helped find bugs and problems in the first editions, and I still am in love with the editor, even when it’s clearly dying.

And while I would love to modernize the editor, making some PRs and fixing some issues, it’s close to impossible to do it. I believe the problem lies on the fact that Atom was an editor, and then Electron was extracted from it. I made the same choice on Chlorine too: I first made the plug-in, then extracted REPL-Tooling from it. Even on a WAY SMALLER codebase (Chlorine), this was HARD: there are still internal, private data that is used inside Chlorine that is not on REPL-Tooling.

Atom is the same. The “setup project” for Atom (prepare Electron, parse cmdline args, etc) is INSANELY huge. There are insane cyclic dependencies (TextEditor depends on components, UI, etc, and these depends back on the editor), there are NPM modules that depend on the editor (so you have code living in Atom that is used on NPM packages, and these also access internal state instead of going thought the public API) and there are outdated web features. There’s also some insanity happening: using newer versions of Node.JS got me 404 trying to run npm install, and even using the node version that Atom says to use in the documentation (that’s also NOT the current LTS version of node, mind you) didn’t work reliably. The only way I was able to install all dependencies was by running yarn install FOUR TIMES, and that did the trick (I got a different error every try, but at least, it worked).

But the problem is not this one: there’s simply too much code that lives “outside” Atom.
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By Maurício Szabo, ago

Performance optimizations in Reagent – part 2

Have I mentioned that it’s a nightmare to install React Devtools in Electron? Turns out, it’s worth it. But it’s still a pain. If you want to try, you’ll need to first install the extension in a chrome-based browser (like Brave, the one I use) and then install it by code. At Chlorine, what I did was to copy the whole extension folder to a devtools directory and then changed the script to load electron to the script below (see the BrowserWindow.addDevToolsExtension):

const path = require('path')
const {app, BrowserWindow} = require('electron')

app.on('ready', () => {
  let browser = new BrowserWindow({
    width: 900, height: 600,
    webPreferences: {nodeIntegration: true}})
  browser.loadURL(path.join('file://', __dirname, '/index.html'))

  BrowserWindow.addDevToolsExtension('./devtools')
})

Originally, the React Devtools was installed at ~/.config/BraveSoftware/Brave-Browser/Default/Extensions/fmkadmapgofadopljbjfkapdkoienihi/4.21.0_0 (tilde is my home folder). If you’re trying to install on Atom editor, you’ll have to open developer tools and issue the following script:

r = require('remote')
r.BrowserWindow.addDevToolsExtension('./devtools') // or the right directory

This command will fail, but somehow when you reload Atom, the React Devtools will be there. There’s only one feature that I use – highlight which elements were updated. And that’s where our performance tuning starts again.
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By Maurício Szabo, ago

Your editor as a query

Some time ago I found out this post: https://petevilter.me/post/datalog-typechecking/. It stroked me as really interesting – because it was an idea to make some IDE not depend on some internal API that only works for a single editor, but somehow make a tooling that’s query able by datalog. This datalog Read more…

By Maurício Szabo, ago

Implementing shadow.remote API

Since version 0.8.0 of Chlorine, there’s a new way to evaluate ClojureScript code: that’s the Shadow-CLJS Remote API. It is basically a new REPL (not nREPL, no Socket REPL) over WebSockets to try to solve problems when translating other REPLs to ClojureScript. So, to understand why these problems exist, I’ll first introduce the difference between ClojureScript and Clojure.

On Clojure, you’re always inside a JVM. This means that compilation happens on the same JVM that your REPL, and your code is running. If you practice REPL-Driven Development, even your tests are running on the same JVM. In practical terms, it means that when you fire up your REPL, you already have everything ready to run code, compile code, and evaluate forms.

On ClojureScript, the compiler is written in Clojure – that means it’s running on the JVM. So, to produce Javascript code you don’t need a Javascript environment – and that’s when things become confusing, because when exactly will you run the REPL? Let’s try from another angle: if you start the REPL on compilation time, you can’t evaluate code (because there’s no Javascript generated, nor any Javascript engine running). If you start the REPL when you run the compiled code, this REPL can become unusable if you stop the Javascript environment, and also you have to coordinate lots of state and translations between formats.
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By Maurício Szabo, ago

The History of Chlorine

Before I even started with Clojure, I was analyzing LightTable – the idea of that editor was to support better integrations between the code you’re writing and the code that’s running. It was a really good experience, but the main problem I had is that it was in the very beginning, with few plug-ins and bad documentation. I tried to make the parinfer plug-in work in the editor, but it had lots of bugs and then I simply changed back to Atom. At the time, proto-repl was the best package to work with Clojure, and I made some small changes to it (so I could add some callbacks to when a new connection to nREPL was made, and other small issues) to improve my workflow.

Fast forwarding a little bit, I started my first Clojure job at Nubank. Most people were using InteliJ, but I felt that by using Atom I had a different approach on problem solving, specially those hard parts where the fast feedback of “run in the REPL and see the results in your editor, then browse over the keys” could give better insights about what’s happening. I tried to implement some features that proto-repl didn’t have at the time (and Chlorine still does not have some) like “automatically add nREPL port”, and “watch expressions” (almost the same as watch variables in a debugger). These ended up in a package called clojure-plus, that still exist today.

I also began to experiment with ClojureScript (at the time, only Figwheel was available – Figwheel-main didn’t even exist!) and found that existing tools didn’t provide the same power that I had with Clojure. It also didn’t have autocomplete, goto var definition, and so on. To ease a little bit these problems, I ended up adding on clojure-plus some CLJS support – when you tried to evaluate a .cljs file, it would try to connect to ClojureScript, reserve a REPL, then evaluate the code over there.
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By Maurício Szabo, ago

Implementing a nREPL Client

Some people asked me on how did I implement the nREPL client on Chlorine. So, I’m writing this post!

nREPL is a simple protocol. It uses “sessions” that are used to isolate evaluation contexts and other things (for example, on Chlorine every connection connect to two REPLs: one “primary” and one “auxiliar” that is used to run commands like autocomplete / goto var definition, and so on). On nREPL, this isn’t necessary: you just connect to a single REPL and use two different sessions. Just for the record, because the way Chlorine works, I didn’t implement it like this (because I would have to rewrite lots of code – maybe in the future).

Now, to explain the protocol, let’s separate things in parts: the first thing I do (and I was already doing in the past) is to connect to a socket. Then, I looked at the documentation for nREPL to understand how to send and receive commands to the REPL. Now, there are some details on the way that every operation is implemented that I simply ignored because it was not necessary to understand then from the perspective of my application…
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By Maurício Szabo, ago

nREPL on… Chlorine?

When I started the Chlorine project, I just thought it would be great if I could target all Clojure-like REPLs that already exist but didn’t have tooling support. At the time, this would include Lumo and Plank, mostly. Also, Shadow-CLJS and Figwheel have some “clunky run-some-code-and-transform-in-cljs” way of working that simply didn’t click with me.

Now, almost a year later, Chlorine supports Clojure, ClojureScript (Shadow-CLJS, Lumo, Plank, or even over clj), ClojureCLR, Arcadia, Babashka, Clojerl (Clojure on Erlang) and Joker (Clojure on Go, also a linter). But the reality is that working with a pure Socket REPL is really hard – a socket REPL works exactly like a regular one, printing namespaces after each code, and so on. Also, there are some strange decisions on some REPLs, mostly likely ClojureScript (that is the second most used Clojure flavor), so things are not always easy. To put things in perspective, currently Chlorine uses 3 ways to evaluate code: It uses unrepl, that only works on Clojure, or uses internal APIs of shadow-cljs (that obviously only works for shadow-cljs), and for other implementations it uses a kind of a hack – it evaluates the code, inside a try…catch, and it returns a vector where the first element is a symbol in a specific format that Chlorine will understand and then link that with the response. This “hacky way” is currently being used for every other implementation except Clojure and Shadow-CLJS. Things work (autocomplete works too), but it is not pretty and sometimes have strange results.

As a matter of fact, I was already thinking about removing UNREPL (it’s really hard to implement new features on it, and some good ideas only work in theory – for example, the ability to evaluate long strings / collections and render only a part at a time aren’t that good with lots of edge-cases) and, to do it, I though about a better, non-hacky way to evaluate things on some Socket-REPLs (that, again, would only work on some REPLs – ClojureScript REPLs will probably never support “upgradable REPLs” because of the way they work) – the only thing that I had to understand is how to implement this “upgraded REPL”…

Then, recently, Babashka added an initial support for nREPL, with an insane low amount of lines. So, I’ve tried to implement a way to evaluate code over nREPL… and it was really simple to do it, using a npm library that already did it. But implementing like this meant that the user would need to know if the host/port to connect is a Socket REPL, or a nREPL (and the user does not know – lots of tools like lein and shadow-cljs show an nREPL port to be connected).
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By Maurício Szabo, ago