38 lines
1.6 KiB
Text
38 lines
1.6 KiB
Text
module
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@[expose] public section -- TODO: remove after `congr_eq` fixed
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open List
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theorem eraseP_eq_nil_iff {xs : List α} {p : α → Bool} : xs.eraseP p = [] ↔ xs = [] ∨ ∃ x, p x ∧ xs = [x] := by
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induction xs with grind
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theorem eraseP_ne_nil_iff {xs : List α} {p : α → Bool} : xs.eraseP p ≠ [] ↔ xs ≠ [] ∧ ∀ x, p x → xs ≠ [x] := by
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induction xs with grind
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theorem length_eraseP_of_mem (al : a ∈ l) (pa : p a) :
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length (l.eraseP p) = length l - 1 := by
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grind
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theorem eraseP_filterMap' {f : α → Option β} {l : List α} :
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filterMap f (l.eraseP (fun x => match f x with | some y => p y | none => false)) = (filterMap f l).eraseP p := by
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grind
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theorem eraseP_append_left {a : α} (pa : p a) {l₁ : List α} {l₂} : a ∈ l₁ → (l₁ ++ l₂).eraseP p = l₁.eraseP p ++ l₂ := by
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grind
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theorem eraseP_append_right {l₁ : List α} {l₂} (h : ∀ b ∈ l₁, ¬p b) :
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eraseP p (l₁ ++ l₂) = l₁ ++ l₂.eraseP p := by
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grind
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theorem head_eraseP_mem {xs : List α} {p : α → Bool} (h) : (xs.eraseP p).head h ∈ xs := by
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-- This had previously been a `grind` lemma,
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-- but it is quite aggressive as it initiates `Sublist` based reasoning.
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grind [Sublist.head_mem]
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theorem getLast_eraseP_mem {xs : List α} {p : α → Bool} (h) : (xs.eraseP p).getLast h ∈ xs := by
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-- As above, this had previously been a `grind` lemma.
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grind [Sublist.getLast_mem]
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theorem set_getElem_succ_eraseIdx_succ
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{xs : Array α} {i : Nat} (h : i + 1 < xs.size) :
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(xs.eraseIdx (i + 1)).set i xs[i + 1] (by grind) = xs.eraseIdx i := by
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grind (splits := 10)
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