> For example a common failure mode in my work’s codebase is that some function will take something that is indexable by ints. The type could be anything, it could be List, Tuple, Dict[int, Any], torch.Size, torch.Tensor, nn.Sequential, np.ndarray, or a huge host of custom types! And you better believe that every single admissible type will eventually be fed to this function. Sometimes people will try to keep up, annotating it with a Union of the (growing) list of admissible types, but eventually the list will become silly and the function will earn a # pyre-ignore annotation. This defeats the whole point of the pointless exercise.

You are looking for protocols. A bit futzy to write once but for a heavily trafficked function it's woth it.

If your JIT compiler doesn't work well with protocols... sounds like a JIT problem not a Python typing problem