e5393cf6bc
This PR fixes a bug in the `cases` tacic introduced in #3188 that arises when cases (not induction) is used with a non-atomic expression in using and the argument indexing gets confused. This fixes #8360.
7 lines
374 B
Text
7 lines
374 B
Text
axiom thm.{u_1, u_2} {α : Type u_1} {β : Type u_2} (f : α → β)
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(motive : List α → List β → Prop) (case1 : motive [] [])
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(case2 : ∀ (a : α) (as : List α), motive (a :: as) (f a :: List.map f as)) (l : List α) : motive l (List.map f l)
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theorem map_isNil (f : α → β) (l : List α) :
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List.map f l = [] ↔ l = [] := by
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cases l using thm f <;> simp
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