Export Flow types as part of the module

[Beanow]

This is a:

• [ ] Bug Report
• [x] Feature Request
• [ ] Question
• [ ] Other

Which concerns:

• [x] flow-runtime
• [ ] babel-plugin-flow-runtime
• [ ] flow-runtime-validators
• [ ] flow-runtime-mobx
• [ ] flow-config-parser
• [ ] The documentation website

---

What is the current behaviour?

Currently, the flow-runtime library does not export it's Flow types as part of the module.

---

What is the expected behaviour?

Incorrect usage of flow-runtime without babel should trigger Flow errors.

// @flow

import t, {type Type} from "flow-runtime";

opaque type PositiveNumber: number = number;

// Example refined type.
const PositiveNumberType: Type<PositiveNumber> = t.refinement(
  t.number(),
  (x: number) => {
    if (x < 0) return "must be positive";
  }
);

// Signature is accepts(input: any): boolean
// But we're passing more arguments and expecting wrong return type.
const _: string = PositiveNumberType.accepts(1, 2, 3, 4);

// Also should be caught by static Flow checks.
() => PositiveNumberType.methodDoesntExist();

---

Which package versions are you using?

flow-runtime: 0.17.0