feat: List.unattach and simp lemmas #5550
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nomeata
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Oct 1, 2024
nomeata
reviewed
Oct 1, 2024
Co-authored-by: Joachim Breitner <[email protected]>
digama0
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Oct 2, 2024
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| If not, usually the right approach is `simp [List.unattach, -List.map_subtype]` to unfold. | ||
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| def unattach {α : Type _} {p : α → Prop} (l : List { x // p x }) := l.map (·.val) |
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Like attach, this needs an implemented_by version which uses an unsafeCast so that it is O(1)
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