[seeekr]

To save others the click: Their issues were simply that Swift has no fast JSON impl, and in Rust, when using serde (most popular library handling JSON marshalling), it leads to binaries getting a bunch bigger. That's it. So yeah, same perspective -- unless either of the above matter in your case (in 90%+ of cases they don't), JSON is just fine from a perf perspective.

[packetlost]

Serde is a rather chunky dependency, it's not just a matter of binaries getting bigger, but also compile times being dramatically slower.

IMO CBOR would be a better choice, you aren't limited to IEEE 754 floats for your numeric types. Yeah, some (de/en)coders can handle integer types, but many won't, it's strictly out of spec. I don't think building something as fundamental to an OS as relying on out-of-spec behavior is a great idea. It will result in confusion and many wasted hours sooner or later.

[Joker_vD]

> CBOR would be a better choice, you aren't limited to IEEE 754 floats for your numeric types.

The other side of this coin, of course, is that now you have to support those other numeric types :) My usual languages of choice somehow don't support "negative integers in the range -2^64..-1 inclusive".