Records

A type declares a named record — a fixed set of named, typed fields. Records describe the shape of values, function parameters, and the backing type of every block.

Declaring a record type

type Dog {
  name: utf8
  age:  u32
}

let rex = Dog { name: "Rex", age: 4u32 }

extends

A record may extends another, inheriting all its fields. The child type is a structural superset; it satisfies any context that accepts the parent.

type Dog {
  name: utf8
  age:  u32
}

type Pet extends Dog {
  breed: utf8
}