feat: add difference on DHashMap/HashMap/HashSet
#11212
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TwoFX
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Nov 18, 2025
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Lemma statements about diff look good! Don't forget to use the SDiff notation as the normal form once you implement the definition on the user-facing types.
wkrozowski
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DHashMap/HashMap/HashSet [Work in progress]DHashMap/HashMap/HashSet
TwoFX
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Nov 25, 2025
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This is mostly looking good now.
| case h_2 => rfl | ||
| exact dl₁ | ||
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| theorem getValueCast?_filter_contains_eq_false [BEq α] [LawfulBEq α] |
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If there is no false in the theorem statement, then there should be no false in the name. This lemma should be called getValueCast?_filter_not_contains. The same applies to many other lemmas in this file.
| {l₁ l₂ : List ((a : α) × β a)} {k : α} | ||
| (dl₁ : DistinctKeys l₁) : | ||
| getKey? k (List.filter (fun p => !List.contains (l₂.map Sigma.fst) p.fst) l₁) = | ||
| if containsKey k l₂ = true then none else getKey? k l₁ := by |
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Suggested change
| if containsKey k l₂ = true then none else getKey? k l₁ := by | |
| if containsKey k l₂ = true then none else getKey? k l₁ := by |
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This PR adds support for difference operation for
DHashMap/HashMap/HashSetand proves several lemmas about it.