Configure mypy and type annotate the code

[aaaandrzej]

Fixed #35

This PR adds mypy to this project and the required types to the codebase.

It also adds a bunch of TODOs as mypy uncovered a couple of issues within the code, like inconsistent types or missing returns. I didn't want to introduce any significant changes to the code as part of this PR so I decided to let mypy ignore these for now, but with relevant TODOs so these can be addressed later.

Running mypy --show-error-codes --pretty --strict . on this code:
Success: no issues found in 16 source files

Running the same command on recent master:
Found 370 errors in 14 files (checked 16 source files)

[ClasherKasten]

Round 1 and overall it looks very good.
I noticed not all files have from __future__ import annotations at the top of the file. Please make sure this import is present.

[ClasherKasten]

Eventually I'm blind, but i don't see when history would contain a None.

[aaaandrzej]

See history of a random game, just tested setting a breakpoint in main.py:

history
[[<src.Move.Move object at 0x105a0d2a0>, None], [<src.Move.Move object at 0x105a0d0f0>, None], [<src.Move.Move object at 0x105a7ad70>, None], [<src.Move.Move object at 0x105a7acb0>, None], [<src.Move.Move object at 0x105a56500>, None], [<src.Move.Move object at 0x105a56440>, None], [<src.Move.Move object at 0x105c3a5c0>, None], [<src.Move.Move object at 0x105c3a680>, None], [<src.Move.Move object at 0x105a36620>, None], [<src.Move.Move object at 0x105a36590>, None], [<src.Move.Move object at 0x105c9c400>, None], [<src.Move.Move object at 0x105c3b130>, None], [<src.Move.Move object at 0x105c9c070>, None], [<src.Move.Move object at 0x105c1fd90>, <src.Bishop.Bishop object at 0x105a0c2b0>], [<src.Move.Move object at 0x105cf2a70>, None], [<src.Move.Move object at 0x105cf2e00>, None], [<src.Move.Move object at 0x105ce26e0>, None], [<src.Move.Move object at 0x105ce1fc0>, None], [<src.Move.Move object at 0x105d6af80>, None], [<src.Move.Move object at 0x105d6bd30>, <src.Pawn.Pawn object at 0x1059dff40>], [<src.Move.Move object at 0x105a65ab0>, None], [<src.Move.Move object at 0x105a64f70>, <src.Pawn.Pawn object at 0x105a0c100>], [<src.Move.Move object at 0x105cc0b80>, None], [<src.Move.Move object at 0x105cc0790>, None], [<src.Move.Move object at 0x105c163e0>, None], [<src.Move.Move object at 0x105c16d70>, None], [<src.Move.Move object at 0x105c56d70>, None], [<src.Move.Move object at 0x105c57790>, <src.Pawn.Pawn object at 0x1059dfbe0>], [<src.Move.Move object at 0x1068002e0>, None], [<src.Move.Move object at 0x106800700>, <src.Knight.Knight object at 0x105a0c250>], [<src.Move.Move object at 0x10688b7f0>, <src.Queen.Queen object at 0x106800f70>], [<src.Move.Move object at 0x10688bd00>, <src.Pawn.Pawn object at 0x1059dffa0>], [<src.Move.Move object at 0x106a3a4d0>, None], [<src.Move.Move object at 0x106a39fc0>, None]]

[ClasherKasten]

history is declared to be list[list] which is automatically translated to list[list[Any]]. So I assume mypy isn't happy for the following reasons:

• Line 166: mypy can't infer the return type because the element which is accessed (history[-1][0] where [0] is the important part) is declared to be Any
• Line 171: same as in line 166. mypy can't infer what type history[-1][0].piece is because history[-1][0] is already Any.

In connection with this it would be an idea to change the type of history to be list[tuple[Piece, Optional[Piece]]]. And all the places where this type is expected have to be changed too.

[aaaandrzej]

This makes sense, I think you meant list[tuple[Move, Optional[Piece]]] though. See if this makes sense now.

[ClasherKasten]

I think you meant list[tuple[Move, Optional[Piece]]] though

Yeah, you're right with that.

[aaaandrzej]

Discussed fixes pushed, feel free to re-review when you have a sec.

[ClasherKasten]

I felt so free and resolved the merging conflict created by merging #43.