[tonygrue]

(I worked on an early version of PyAnnotate.)

The main difference is that pytype is a static analyzer (i.e. it inspects the code and tries to figure out what types various things are), whereas PyAnnotate is a profiler hook, so you have to run your code and it observes types as your code runs.

Both have their pros and cons. While static analysis (in my personal opinion) would be ideal because you don't have to run your code, and in theory it can be much more complete, it's also much harder (often impossible) in Python. The runtime analysis of PyAnnotate has a lot of downsides (it doesn't give you types for code that it didn't observe run and it can't know if it has seen all the particular types for a parameter or return). The upside is that it was quick to implement something useful and it gets you quickly to pretty descent type annotations for your main code paths. Which is nice, because in a large untyped codebase it effectively lays down a rough draft of type annotations, making it a lot easier to fix up and fill in edge cases by hand.

[carapace]

There was a thing called PySonar by Yin Wang. It's sort of gone now but you can still find copies around the net.