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This works because casts are allowed to quietly create values whose types are wrong. It would have been better if the cast added a runtime check, or at least w

This works because casts are allowed to quietly create values whose types are wrong. It would have been better if the cast added a runtime check, or at least we distinguish sound (checked) and unsound casts the way C++ does. I think Haskell avoid this by actually requiring you to write sound conversion functions between phantom types (it helps that phantom types don't involve any visible state at runtime).

diarrhea 2y ago
As a TypeScript beginner, I was bitten by this. Typing in TypeScript feels quite bad for some reason; a lot of effort for effects which are still potentially wrong at runtime. I didn’t struggle so much in Python, Rust or C#, for example. Python is surprisingly… sound? in comparison. It can do nominal as well as structural typing.