Type Introspection Mechanism

[gajus]

Type Introspection Mechanism

[phpnode]

hey, thanks! Yes I'm absolutely interested in this, so right now you can do stuff like this:

import t, {reify} from 'flow-runtime';
import type {Type} from 'flow-runtime';

type User = {
  id: number;
  name: string;
};

const UserType = (reify: Type<User>); // keeps flow happy, you could just reference User directly.

// every type can be converted back to its flow representation with toString():
console.log(String(User));
// certain types, like type aliases support a boolean 
// argument on toString() indicating whether or not to include the
// full declaration:
console.log(UserType.toString(true));

UserType.getProperty("id").unwrap().assert(123);
UserType.getProperty("name").unwrap().assert("Sally");
UserType.getProperty("name").unwrap().assert(false);

I'd like to have a way to serialize and deserialize the types themselves, but whatever format that ends up being needs some way to support cycles.

[DylanRJohnston]

Is there anyway to iterate over the properties of the objects? flow-io has UserType.props? But the babel transformer for this runtime is super useful.