typeable-promisify

• Wrap any node-style callback function with a promise.
• Allows you to specify your own type annotations.
• Strongly typed.

// @flow
import promisify from 'typeable-promisify';

let writeFileAsync = (filePath: string, fileContents: string): Promise<void> => {
  return promisify(cb => writeFile(filePath, fileContents, cb));
};

writeFileAsync('fileName', 'fileContents').then(() => {});