Whenever someone writes bad things™ about some language, one of the language's fanboys shows up and starts nitpicking! Yes, now is the time!
> Another bad part is Rust’s JSON handling. It badly needs macros which make things easier.
Actually this is not the end of the world. As you mentioned, Rust's JSON library supports `ToJson` for primitive types, but also provides compile-time code generation for arbitrary `struct`s. Quoting the code from my project:[1]
#[derive(RustcDecodable, RustcEncodable)]
struct Msg {
cmd: String,
id: i32,
x: Option,
y: Option,
speed: Option,
}
What the mystical `#[derive]` thing does is to direct the compiler to create the boilerplate for converting the `struct` to/from a string automatically. So, now you can do this:
// Decoding a JSON string
let text = r#"{"cmd": "move", "x": 5, "y": 10, "speed": 200}"#;
let decoded: Msg = json::decode(text);
// Encoding a Msg object to JSON
let msg = Msg { cmd: "new", x: 10, y: 20 };
let encoded = json::encode(msg);
The `Msg` struct is full of `Option`s because my project allowed many fields to be missing, but if the JSON messages in your protocol are in fairly similar format, you can eliminate most of them.
One more benefit of this approach is that it type checks. If the JSON you received is missing some fields that are not defined as `Option`, the decoding process produces an error! So you can be certain that you're handling a valid JSON after the decoding stage. This is analogous to schemaless vs. schema-enforced database design.
> Compared to many static languages, the handlers look tidy. Compared to dynamic languages, they’re terrible.
This is the property of the Iron framework, not of the Rust language itself! Another web framework for Rust, namely Nickel.rs[2], provides much simpler APIs.
I believe the author of Iron is trying to establish essential things first, and build more "user friendly" APIs on top of them. (FWIW, the Rust project itself follows the similar strategy.)
[1] https://github.com/barosl/pgr21-online-server/blob/master/sr...
[2] http://nickel.rs/