Tags / async

fnl-http is my current passion project - I spend a lot of free time tinkering with it, and the last week was spent on testing and fixing bugs. As you may know, I made a testing framework, called fennel-test, which has a dedicated test runner, and a set of macros for writing tests.

In the last post two weeks ago I described the process of making an asynchronous HTTP/1.1 client from scratch (minus the socket part). At the end, I mentioned that there’s a lot more to implement: Now, of course, that’s not all that needs to be implemented.

A while ago, I made a library for asynchronous programming in Fennel. It’s based on Clojure’s core.async vision of asynchronous programming using only channels. As an experiment, I’ve added a TCP support layer in that library, allowing one to create a TCP channel, and use it in the same way as a regular channel.

Lately, I’ve been working on async.fnl in my spare time and realized that the previous code that I used to schedule timers was terrible. Well, realized isn’t an appropriate word here, because I knew it back when I first implemented it, I just didn’t bother to make it better until I had a fully working library.

After I explored asynchronous programming in my first naive implementation a few years ago, I was hooked on the idea of asynchronous communication in programs. Motivated to take this concept further I’ve created the fennel-async library that I’ve shown at FennelConf 2022. While this library works, and I’ve managed to write a simple socket-based REPL and integrate it into Emacs as an experiment, I wasn’t satisfied with the implementation.

TIL that Emacs Lisp has had generators since 2016, and generators are a cool feature in any language in my opinion! In short, Emacs has the generator.el package as it’s part since version 25.1. The generators are implemented via transforming code and act like iterators, even most of the functions are called iter-something.

I’ve been into clojure.core.async lately, and I like the overall design of this library - it’s simple and easy to understand. However, at work, we use manifold in our projects, mainly because it is supported by the aleph server, which was chosen because it can asynchronously read data coming from the client.

Quite recently I’ve been working on my asynchronous programming library for Fennel, and fiddling with clojure.core.async at the same time for my other project. I’ve found an interesting function, called pipeline-async, which seemed to be a good fit for my task. Here’s the documentation for this function:

Lately, I’ve been into understanding asynchronous programming. Since my background is mostly bare metal C, which has no asynchronous programming whatsoever (apart from running on multiple chips, and communicating via shared memory), and I did only a little bit of C++ and Rust, it’s fair to say, that async is pretty new for me.