8304bfe237
This PR adds support for anonymous equality proofs in `match` expressions of the form `match _ : e with ...`. Closes #6759.
49 lines
1.1 KiB
Text
49 lines
1.1 KiB
Text
/-!
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# Match expressions with unnamed equality proofs
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https://github.com/leanprover/lean4/issues/6759
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Tests that `match` expressions successfully elaborate when providing a hole instead of an identifier
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to which to bind the optional equality proof.
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-/
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def getLast? {α : Type} (a : Array α) : Option α :=
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match _ : a.size with
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| 0 => none
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| m + 1 => some a[m]
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/-- info: some 4 -/
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#guard_msgs in
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#eval getLast? #[3, 4]
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def getLasts? {α : Type} (a b : Array α) : Option (α × α) :=
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match _ : a.size, _ : b.size with
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| 0, _ => none
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| _, 0 => none
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| m + 1, n + 1 => some (a[m], b[n])
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/-- info: some (4, 5) -/
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#guard_msgs in
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#eval getLasts? #[3, 4] #[5]
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def getLasts?' (a b : Array α) : Option (α × α) :=
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match _ : a.size, h : b.size with
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| 0, _ => none
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| _, 0 => none
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| m + 1, n + 1 => some (a[m], b[n]'(h ▸ Nat.lt.base n))
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/-- info: some (4, 5) -/
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#guard_msgs in
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#eval getLasts?' #[3, 4] #[5]
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theorem test_tactic (n : Nat) (h : n - 1 > 2) : n - 1 > 2 := by
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match _ : n - 1 with
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| 0 =>
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have : n - 1 = 0 := by assumption
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rwa [this] at h
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| n' + 1 =>
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have : n - 1 = n' + 1 := by assumption
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rwa [← this]
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