Extending Python's concurrent.futures.Future (Promise) object with missing chaining API like .then().
While Futures (aka Promises) are formally specified and available as part of Python as of v 3.2+, and is available as backported module for Python versions v.2.x, standard implementation is lacking any formal or convenient API for the most frequent use of Promises - chaining.
JavaScript Promises/A+ API have then-ability as part of the spec.
This project takes standard concurrent.futures.Future Python class and extends it with borrowed .then() behavior from JavaScript Promises.
pip install futures_then
In [1]: from futures_then import ThenableFuture as Future
In [2]: f1 = Future()
In [3]: f2 = f1.then(lambda v: v + ' transformed')
In [4]: f1.set_result('future')
In [5]: f2.result()
Out[5]: 'future transformed'