Support for Python PEP 677 in Python TextMate grammar

[alexr00]

• Editor name and version: VS Code
• Platform: Any
• Color scheme: Any
• MagicPython version:
• A sreenshot:
• 5-10 lines of surrounding code:

VS Code includes a TextMate grammar for Python. Draft PEP 677 introduces a new syntax for annotating callable signatures. This PEP hasn't been ratified, but it's likely to be in the near future. I recently added support for this feature in pyright (and therefore, in pylance as well). The TextMate grammar will need to be updated to accommodate this new syntax. Currently, it causes VS Code to display the -> token in red.

Originally from @erictraut in microsoft/vscode#139393

[JelleZijlstra]

Note this PEP was rejected, so it probably doesn't make sense to add support to MagicPython now.