Should TryFrom be implemented for Value?

[amandasaurus]

serde_json::Value has various as_* methods which allow conversion to the underlying enum (e.g. as_bool, as_str). Rust now has a TryFrom trait. Should TryFrom be implemented for Value for things like this? I'm willing to add this myself, but first, I'd like to check it would be accepted, or if there's a good reason it hasn't been implemented yet.

[dtolnay]

I think I would prefer not to add those. This use case is already covered by the Deserialize trait in a more flexible way that works for extracting a vector, struct etc as well.

let x = u64::deserialize(&value)?;

[amandasaurus]

Deserializing to a u64 (etc) isn't much of a problem, right? But what about Vec<_>s or Strings? (i.e. serde_json::Value::Array or serde_json::Value::String) Is there an easy way to “If this is an array, return a refence to a slice, if not return None (or Err(_))”?. And likewise for String and &str?

If you're using JSON know the data layout, then serde's Serialization/Deserialization makes a lot of sense to convert to proper Rust structs. But I think people will often have a blob of JSON they will need to work with “dynamically”. The std::convert traits are very useful here, no?

For a geojson bug report, I attempted to use the T::deserialize approach, (patch here). It works for u64/etc. But how can I (optionally) return a reference to a slice for arrays (etc.)?

[amandasaurus]

Given that From<u64> for Value (etc.) is implemented, surely the reciprocal TryFrom<Value> for u64 (etc.) should be implemented too?