flow.js

// Make complex type from primitive types
type Person = {
  name: string,
  age: number,
}

// Test it.
const joe: Person = {
  name: 'Joe',
  age: 60,
};

// Generic type.
const persons: Array<Person> = [{ name: 'Joe', age: 60 }]

// Some other type.
type Product = {
  name: string,
  owner: Person
}

// Test it.
const table: Product = {
  name: 'Table 123',
  owner: joe
}