> Do you believe that a future mypy plugin could replace pipeline type > checks in Beam, or are there limits to what it can do? >
mypy will get us quite far on its own once we completely annotate the beam code. That said, my PR does not include my efforts to turn PTransforms into Generics, which will be required to properly analyze pipelines, so there's still a lot more work to do. I've experimented with a mypy plugin to smooth over some of the rough spots in that workflow and I will just say that the mypy API has a very steep learning curve. Another thing to note: mypy is very explicit about function annotations. It does not do the "implicit" inference that Beam does, such as automatically detecting function return types. I *think* it should be possible to do a lot of that as a mypy plugin, and in fact, since it has little to do with Beam it could grow into its own project with outside contributors. -chad
