[ty] Implement disjointness for TypedDicts #22044
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oconnor663
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AlexWaygood,
carljm,
dcreager and
sharkdp
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Diagnostic diff on typing conformance testsNo changes detected when running ty on typing conformance tests ✅ |
oconnor663
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Dec 18, 2025
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| # TODO: T can't be compatible with both `int` and `bool` at the same time, so these types should be | ||
| # disjoint, regardless of the materialization of `T`. |
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Is this sort of "one dynamic type winds up in multiple fields" situation ever something we reason about? Is there a name for this?
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hmm, yeah, this is pretty interesting. No, I haven't come across this problem before, but thinking about it, it must exist for other generic types in our model too. I wouldn't worry about it too much right now, but it could be worth opening a followup issue to discuss it.
oconnor663
commented
Dec 18, 2025
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CodSpeed Performance ReportMerging #22044 will improve performances by 70.52%Comparing Summary
Benchmarks breakdown
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Clippy and Cargo want very different things here. Clippy demands that the numbered list is indented, but that makes Cargo think it's Rust code and start trying to compile it. I don't know how to make them both happy, so I'm making it a regular `//` comment block instead of an actual `///` doc comment, which seems to shut them both up...
AlexWaygood
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TypedDictType::is_disjoint_from_impl
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Dec 18, 2025
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This looks great!! Really good job
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| # TODO: T can't be compatible with both `int` and `bool` at the same time, so these types should be | ||
| # disjoint, regardless of the materialization of `T`. |
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There was a problem hiding this comment.
hmm, yeah, this is pretty interesting. No, I haven't come across this problem before, but thinking about it, it must exist for other generic types in our model too. I wouldn't worry about it too much right now, but it could be worth opening a followup issue to discuss it.
| // 2c. If both sides are immutable, and their types are disjoint. (Because the type in `C` | ||
| // must be assignable to both.) | ||
| // | ||
| // TODO: Adding support for `closed` and `extra_items` will complicate this. |
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This mypy_primer hit is in fact a new false positive: + openlibrary/plugins/openlibrary/lists.py:89:19: error[invalid-key] Unknown key "key" for TypedDict `AnnotatedSeedDict`: Unknown key "key"Previously the type of Edit: This is mistaken, see the next comment. |
This was referenced Dec 19, 2025
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Hmm, actually my comment above is mistaken. |
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This is a preliminary step to tagged union narrowing for
TypedDict: astral-sh/ty#1479