What is Deno?
9 min read
I got to hang with Deno core team member Luca Casonato a couple of weeks ago to discuss a framework he created called Fresh! You can check out Fresh: a new full stack web framework for Deno with Luca Casonato on my YouTube channel.
Transcript of What is Deno?
Nick Taylor: Speaking of Deno. Yeah, we act, I work in Netlify and we use it for our Edge offering. So, uh, if folks are kind of wondering if it's production ready, I would definitely say yes.
Um, so, uh, we're definitely gonna talk about Fresh, which is a new web framework, but I kind of want to touch on Deno a bit first because I'm, I'm somewhat familiar with it, but I know Deno might be something that's new to a lot of folks. So I guess, I guess high level, like what is Deno?
Luca Casonato: Yeah. So Deno's original pitch is that Ryan, the person who originally created Node, um, went like 10 years later or eight years later.
So like have fetch for HTTP server rather than having custom APIs. And, we have module resolution works the same way that it does in the browser. So we like import stuff from URLs and you can use import maps, just like in browsers to, to re map specifiers stuff like that. Okay.
Nick Taylor: Cool. Cool. Yeah. Yeah, no, it's, uh, it, I find the project pretty interesting, cuz like, uh, I, I dropped a link to that.
Talk about, uh, 10 things I regret about Node.js and I, I can't remember when Ryan started working on it, I think it was like three, maybe four years ago. Uh, I'm not positive, but
Luca Casonato: I think may 20 on May 23rd. It was four years ago. So it's been like four and a bit years now.
Okay. Yeah. Quite a while.
Nick Taylor: Yeah. No and yeah, no, I remember, uh, I found the talk really interesting cuz like he was critical of a lot of things of Node, but I think he, if anybody is allowed to be critical about, it's probably the creator of it. Um, yeah. And um, yeah, no. I I'm a big fan of TypeScript. So I found it interesting that he decided to go with TypeScript.
And I know just, just from what I had read, like a few years ago, it was initially, uh, coded in Go, I believe. And then, I'm not sure when, but there was a, a pivot to go to Rust, I believe, but I, I don't know what I mean I know Rust is a very great language. So do you know what the reason for the pivot was?
Like it's safe. Yeah , it's really fast.
Nick Taylor: Okay. Yeah, no, there's a lot of stuff. Uh, I'm still pretty new to Rust, but I, I I'd been learning a bit of it last. Uh, last year, last fall. And, uh, I definitely there's some con well, I definitely love the pattern matching in it, but I, I definitely there's some concepts like, you know, borrowing and all that.
It's, it's an interesting, it's it takes a second to get your head wrapped around it, but it's kinda neat how only one thing can ever own the data, which in theory, and I imagine in practice too means you can never have any kind of, uh, data collisions or issues with concurrency or at least that's, that's like the big thing, isn't it?
Luca Casonato: Yeah. So the, the core principle of Rust is that you can never have two references. To the same bit of mutable data or, sorry. No, you can never have two mutable reference to the same bit of data. Like you can have multiple references to the same data, if you all can only read from the data, that's fine. But yeah, if you want to modify the data, you have to be, you have to have like single ownership over that data at that point in time when you're trying to mutate it, which allows you to make sure that when you're mutating this data, other like threads, for example, can't be in the middle of reading that data.
It can't break them because you're outta sync from them. So that's, and the entire borrow checker and rests memory ownership model is built around the concept that you can only ever have a single mutable reference, to some bit of data. And it like takes a while to wrap your head around.
But like once you do, it's, it's very empowering because it allows you to. To, to build like really fast software, and really safe software, with very little effort. Well I say very little effort, very little effort compared to something like C++, right. Where you have to continuously keep your mind in this space
like, is this safe? Um, where do like, do I need to move this point or, like crazy stuff that you don't need to deal with and rest, cause the compiler will just error, if you do something wrong.
Nick Taylor: Yeah, I know for sure. And, and I know even like the, the Chrome team has started to build out parts of the V8 engine with it, because, because of like, as far as I know, the majority of it's written in C++, and there's like, mm-hmm,
I don't know how many bugs, but there's definitely bugs related to memory management. And they've been slowly plugging in Rust there as well to, uh, to help, um, uh, kind of squash some of those bugs. Um, and it definitely makes sense what you're saying about the garbage collection, because, I used to do C# quite a bit, and it, and it's nice when you don't have to worry about, you know, allocating and deallocating memory, but I can definitely, there is a hit to having the garbage collector, you know, at some point, you know, not that your program seizes up, but there's, there's at one point, you know, like somebody's gotta take out the trash, you know, and, and I, and it definitely makes sense what you're saying.
If the two languages are garbage collected, then I could see that being an issue. Yeah.
Luca Casonato: Like they're, they're continually fighting with each other, like they're not coordinating on when. Gonna do these pauses to do garbage collection. So like they might happen half a second apart from each other, which that's probably fine, but like, they might also just happen right after each other.
Then you have like a lockup of 200 milliseconds in your program where they're both doing garbage collection.
Nick Taylor: And I guess, I guess another reason I could think of why, the move to Rust might have happened too, is a web assembly. I imagine as well? Cuz like, uh, like I know web assembly started off with Rust.
Luca Casonato: I think we like originally when the switch was made, this was not really something we considered at all, but over time, this is really like proven to be insanely useful. Like a lot of our internal infrastructure that's built it's for native code in, in the binary, in the CLI binary. We also have WASM builds for it that you can just run on the Edge.
Okay. Um, in WASM containers.
Nick Taylor: That's pretty cool. Yeah. Yeah. Okay. Nice. And then, uh, so, and then, yeah, we we'll definitely get to Fresh, uh, shortly, but, uh, and obviously. Uh, TypeScript's seem to make sense because, well, one it's definitely a rising in popularity. It's it's, uh, people might not realize this, but TypeScript's been around since 2012, like cuz I, I started using TypeScript.
Luca Casonato: Yeah.
Nick Taylor: Yeah. Yeah. For sure.
Luca Casonato: And the amount of benefit it provides, like even if it didn't do type checking, even just for like editor completions is just so phenomenal.
It's just worth it. Just alone for editor completions.