json VS watt

Oh wow. So serde_json doesn't roundtrip floats by default, it uses some imprecise faster algorithm https://github.com/serde-rs/json/issues/707

Good thing there's msgpack I guess.

tokio / hyper / toml / serde / serde_json / json5 / console

Serde JSON, an extension of the serde crate that enables the serialization and deserialization of Rust structs.

To serialize and deserialize data, we'll employ the popular serde crate along with serde_json. This will allow us to easily convert between Rust types and JSON when working with API requests and responses. For async operations we'll use the Rust futures crate.

From the Cargo.toml file above, we can see that the Perseus version at the time of publication is 0.4.2 and has the following dependencies that are common to both the engine side (server-side) and client side of a Perseus application: sycamore, serde, and serde_json.

serde_json

Number parsing uses a fairly naive but uses a lossless algorithm in musli-json. In serde_json they use a fork of lexical I haven't wrapped my head around. I wanted something simple to start with.

Your best best would be to use an enum. Either your own or something like the one from serde_json depending on what you are trying to do.

Don't do that if you care about memory usage. In your toy program, I wouldn't be surprised if memory usage was a lot better if you used Box instead. (even if it doesn't look like it, you can handle almost all the use cases of serde_json::Value with it, often not much less convenient)

The precompiled binary is not a sandboxed WASM binary. Despite the name "watt" it has nothing to do with https://github.com/dtolnay/watt . You can look at the actual code to see for yourself.

* Related: watt is one approach to pre-compile proc-macro crates using WASM.

In addition to thiserror and anyhow, our resident superhuman Rust-improving Robot, dtolnay, also developed an experiment in distributing precompiled proc macros as WebAssembly named Watt and, though I never bothered to create a Zulip account so I don't know what was said, I'm told there has been discussion around the idea of implementing something in that vein.

I think when we have Cranelift, Mold, and maybe Watt all working together then compile times will basically be a non-issue. It'll be a few years though.

Check out https://github.com/dtolnay/watt - it's a really interesting solution to the problem!

I really like the idea of Watt: https://github.com/dtolnay/watt Run macros in a wasm sandbox so they can't touch anything you don't explicitly allow.

I really wish there was more interest in getting something like Watt upstreamed.