[IshKebab]

Std definitely differs from other crates:

1. There's only one version so you can't end up with multiple copies of the crate.

2. It is precompiled, so it doesn't bloat your target directory or compile time.

3. It is able to use unstable features without using the nightly compiler.

It's a totally reasonable approach. Many other languages have JSON support in their standard libraries and it works fine. I'm not sure I'd want it, but I wouldn't say it's an obviously bad idea.

[kelnos]

> Many other languages have JSON support in their standard libraries and it works fine. I'm not sure I'd want it, but I wouldn't say it's an obviously bad idea.

I would say it's a bad idea. JSON is, for lack of a better (less derogatory) term, a data-format fad. If Rust had been designed back in 2000 we'd be having this discussion about XML. Hell, consider Javascript (where JSON comes from), with XHR: remember that stands for "XMLHttpRequest"! Of course it can be used with data payloads other than XML; fortunately the people who added it weren't that short-sighted, but the naming is an interesting historical artifact that shows what was only fleetingly dominant at the time as an API data format.

In another 20 years, when Rust is hopefully still a relevant, widely-used language, we may not be using JSON much at all (and oof, I really hope we aren't), and yet the Rust team would still have to maintain that code were it in the stdlib.

Consider also that Rust's stdlib doesn't even have a TOML parser, even though that seems to be Rust's configuration format of choice.

[IshKebab]

Ha I really hope you're right about JSON being a fad, and something better will come along.

I would bet against it though. JSON's flaws (ambiguous spec re numbers & duplicate keys etc; no comments, strings aren't zero copy...) are pretty minor compared to XML's (completely wrong data model, insanely verbose, not even basic data types).

There was much more motivation to replace XML than JSON.

Also even though XML has been broadly replaced, it's still widespread and I don't think it would be out of place to have it in a standard library. Go has, and Go's standard library is one of its highlights.