The Rust and WebAssembly domain working group wants to cultivate a stable, batteries-available, and production-ready ecosystem for Rust and Wasm development in 2019.

To further that goal, we are creating Gloo, a modular toolkit for building both:

small, targeted Wasm modules that integrate into a larger JavaScript system, and

whole Web applications written in Rust.

Gloo’s goals for Wasm are similar to what the Async Ecosystem working group’s Tide project intends to do for server-side Web development:

The name “Tide” refers to “a rising tide lifts all boats”; the intent is to improve sharing, compatibility, and improvements across all web development and frameworks in Rust.

The Utility High-Level Libraries and Frameworks Provide

We use high-level libraries and frameworks instead of using Web APIs directly because we want abstractions with which we can naturally express ourselves. We outsource non-business logic concerns so that we can create more robust libraries and applications more quickly than we otherwise would. For example, the desires people might have include:

They prefer describing how they want the DOM to look like right now, rather than enumerating a list of modifications that will transform its current state into their desired state. Therefore, they use an immediate-mode virtual DOM library.

They prefer thinking in terms of Rust types, not about the raw, serialized bytes in a fetch ed HTTP response body or about object stores in Indexed DB. Therefore, they use derive -based serialization and deserialization with serde .

There are many different ways to approach high-level APIs, and people have lots of differing opinions about which way is best! Designing these APIs well is difficult: we have correctness, ergonomic, and performance concerns.

How Gloo Fits In

Gloo aims to be both a collection of small, focused utility crates and an umbrella crate that pulls all the utilities together into a single package.

Our goals with Gloo are:

To bolster the Rust and WebAssembly crates ecosystem. Pick and choose utility crates even if you aren’t using the whole umbrella Gloo crate, or if you are using some other Rust and Wasm framework. We have some crates like this today — for example the console_log crate — but we would like to intentionally grow more shared utility crates across the ecosystem.

To wrap these utilities up in an umbrella crate so that your new project can hit the ground running. This umbrella crate will be a thin wrapper around the utility crates, and provides defaults wherever multiple (perhaps opinionated) choices exist. To keep the umbrella crate small, we should be constantly pulling code out into new shared, utility crates. For the more opinionated bits, like virtual DOM rendering or web components, the umbrella crate should prefer interfaces over implementations, so that different implementations with different approaches are swap-able.

Gloo is far from ready right now! The project has only just begun. But we want to build Gloo as a collective and in an open way, so we are announcing it early and inviting you to come help us design and build it.

Want to get involved?

Where We’re Starting

At the 2019 Rust All Hands meeting in Berlin, we found that it was useful to categorize Web libraries by whether they were opinionated or not. We all want idiomatic-Rust wrapper crates around raw web-sys timers and requestAnimationFrame etc, and there isn’t a whole lot of design work that needs to happen for this. For many of these kinds of crates, we are ready to dive into implementation. On the other hand, for the more opinionated bits, like virtual DOMs and state management, we need to do exploratory design work before committing to a particular approach.

We’ll start exploring the design space of the latter group in a series of follow up blog posts. In the meantime, if you want to get involved, start hacking on some of the utility crates, or brainstorm about designs, then check out some of the issues on Gloo’s GitHub repository.