bitdispenser.dev/content/english/posts/songlify.md

title	description	tags	date
Building a Telegram bot in Rust: a journey	An adventure through Rust and Telegram	blog tech rust telegram	2022-01-02T15:32:00+02:00

Some time passed since the last article I wrote there. A lot of stuff happened meanwhile, especially with COVID, but here we are again. While busy dealing with the mess of real life tasks, three months ago I started to write a little bot for Telegram in Rust. It is a simple one, but I consider the journey interesting and worth of writing it down.

Telegram bots

Telegram bots are not something new to me and nowdays are pretty much easy to make, so I consider them like a gym where to try out new technologies and experiment with stuff. I wrote plentiful of them, some of those are open source like for example https://github.com/Augugrumi/TorreArchimedeBot (I checked it out and now it is broken 😭) that was useful when going to University, because it scraped the university free room web page and from there it was able to tell you which rooms where without any lessons and for how much time, allowing you to easily find a place where to study with your mates (yep, we didn't like library too much).

{{< figure src="/content/songlify/telegramscreen.png" alt=A screenshot of TorreArchimedeBot in action. caption=A screenshot of TorreArchimedeBot in action. >}}

Also another one bot worthy of mention is https://github.com/Polpetta/RedditToTelegram, that allowed our D&D group to receive push notifications of our private Subreddit in our Telegram group.

As you can see, all of these bots are quite simple, but they have the added value of teaching you some new programming concepts, technologies or frameworks that can be later applied in something that can be more production environment.

Rust

I started to approach Rust many years ago (I don't remember exactly when). First interaction with it was quite interesting to say at least: there were way less compiler features (for example now the compiler is able to understand object lifetime at compile time most of the time alone, without specifying them) that made it a... not-so-pleasant programming experience. It had potential thought, so by following Rust news I picked it up last year again, noticing that now it has improved a lot and it is more pleasant to write. Meanwhile, also JetBrains developed a good support for IntelliJ, so now it is even possible to debug and perform every operation directly from your IDE UI.

World collision: Rust + Telegram

One of the features I wanted to learn this time regarding Rust was the asynchronous support it offers. Rust started to have async support with Tokio framework, and recently the Rust team started to build the asynchronous functionality inside Rust itself. Even if in the first steps, it looks promising and the idea of a low-level language, without GC, with automatic memory management and so much safety having asynchronous support is exciting to me! 🥳 So the only option left, at this point, was to start messing around with it. I started by picking up one of the many frameworks that provides a layer for the Telegram APIs, Teloxide. In particular, as you can see from its README, one of the examples starts by using #[tokio:main] macro:

use teloxide::prelude::*;

#[tokio::main]
async fn main() {
    teloxide::enable_logging!();
    log::info!("Starting dices_bot...");

    let bot = Bot::from_env().auto_send();

    teloxide::repl(bot, |message| async move {
        message.answer_dice().await?;
        respond(())
    })
    .await;
}

This was the reason I picked it up, given that it looked the most promising by the time I started the project.

Building Songlify

So, after choosing what was going to use to build the bot, I needed a reason to build it.