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Wouldn't this be a nice feature in asyncio.Future?

It does exist actually, as `asyncio.futures._chain_future`: https://github.com/python/asyncio/blob/master/asyncio/futures.py#L411 It is used in `loop.run_in_executor` and `run_coroutine_threadsafe` to connect asyncio futures and concurrent futures together.

As best as I can work out, the only reason that asyncio Future?s don?t behave this way is that asyncio strongly emphasises the use of coroutines to program in this manner.

I agree, I think that's why this function is not exposed. /Vincent