Records in UDL

Our simple TodoEntry is defined in UDL as:

dictionary TodoEntry {
    boolean done;
    u64? due_date;
    string text;
};

All the usual types are supported.

Object references

Our dictionary can refer to obects - here, a User

interface User {
    // Some sort of "user" object that can own todo items
};

dictionary TodoEntry {
    User owner;
    string text;
}

The Rust struct will have owner as an Arc<>.

Default values for fields

Fields can be specified with a default value.

dictionary TodoEntry {
    boolean done = false;
    string text;
};

Optional fields and default values

Fields can be made optional using a T? type.

dictionary TodoEntry {
    boolean done;
    string? text;
};

The corresponding Rust struct would need to look like this:

struct TodoEntry {
    done: bool,
    text: Option<String>,
}

Optional null values

Optional fields can also be set to a default null value:

dictionary TodoEntry {
    boolean done;
    string? text = null;
};