Export Flow types as part of the module

[Beanow]

This is a:

• Bug Report
• Feature Request
• Question
• Other

Which concerns:

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

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What is the current behaviour?

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

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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