mypy and Pydantic compatibilities

[svlandeg]

Both spaCy and Thinc have an optional dependency on mypy, but we've found that sometimes specific versions of these two packages are incompatible. As we can't express complex package dependencies and we don't want to restrict Pydantic too much in order not to lock people in, we've decided to at least document combinations that we've found to be incompatible. Feel free to add to this thread when you encounter such cases.

[svlandeg]

mypy 0.981 and Pydantic 1.8.2 will raise an error

Error importing plugin "pydantic.mypy": cannot import name TypeVarDef

In this case, either downgrade mypy to < 0.970 or upgrade Pydantic to >= 1.9.0.