Typed eventually construct using TypeScript and Promises

eventually.ts

// Example Usage:
eventually(20)(() => fetch('http://i.fail.often.com/data.json'))
  .then(data => console.log(data))
  .catch(e => console.log(e));


function eventually<T>(
  giveUpAfterNumberOfRetries: number,
  nextInterval: (numberOfRetries: number) => number = linearRetryInterval
) {
  return (fn: () => Promise<T>): Promise<T> => new Promise<T>((resolve, reject) => {
    const retry = (retryNumber: number = 1) => {
      fn()
        .then(r => resolve(r))
        .catch(e => {
          if (retryNumber <= giveUpAfterNumberOfRetries) {
            setTimeout(() => retry(retryNumber + 1), nextInterval(retryNumber));
          } else {
            reject(new Error(`Max retries reached. Last error: ${e}`));
	  }
        });
    };
    retry();
  });
}
  
function linearRetryInterval(numberOfRetries: number) {
  return 1000 * (numberOfRetries * 0.5); // 500ms, 1000ms, 1500ms, ...
}

function constantRetryInterval(numberOfRetries: number) {
  return 1000;
}