[jukkaleh]

Mypy needs some extra syntax not provided by standard Python annotations (e.g. local variable annotations, casts), so it makes sense to have the syntax related to static typing clearly different from Python to avoid confusion. C-style annotation syntax also has the benefit of being familiar to a very large programmer population. There will also be a converter from mypy syntax to Python syntax.

[andrewcooke]

just seen this reply; thanks. i encourage you to think again, though. one reason is that you would be more likely to influence the future evolution of python itself if you worked more within the system...