lean4-htt/tests/lean/run/matchtac.lean
Leonardo de Moura 4e99b19a96 fix: expandMatchDiscr cannot be a macro
The `matchType` created by the macro is bad for dependent pattern
matching. The `tst8` and `tst9` at `matchTac` failed to be elaborated
when using the macro.
2020-09-15 13:29:28 -07:00

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new_frontend
theorem tst1 {α : Type} {p : Prop} (xs : List α) (h₁ : (a : α) → (as : List α) → xs = a :: as → p) (h₂ : xs = [] → p) : p :=
by match h:xs with
| [] => exact h₂ h
| z::zs => apply h₁ z zs; assumption
theorem tst2 {α : Type} {p : Prop} (xs : List α) (h₁ : (a : α) → (as : List α) → xs = a :: as → p) (h₂ : xs = [] → p) : p :=
by match h:xs with
| [] => ?nilCase
| z::zs => ?consCase;
case consCase => exact h₁ z zs h;
case nilCase => exact h₂ h
def tst3 {α β γ : Type} (h : α × β × γ) : β × α × γ :=
by {
match h with
| (a, b, c) => exact (b, a, c)
}
theorem tst4 {α : Type} {p : Prop} (xs : List α) (h₁ : (a : α) → (as : List α) → xs = a :: as → p) (h₂ : xs = [] → p) : p :=
by {
match h:xs with
| [] => _
| z::zs => _;
case match_2 => exact h₁ z zs h;
exact h₂ h
}
theorem tst5 {p q r} (h : p q r) : r q p:=
by {
match h with
| Or.inl h => exact Or.inr (Or.inr h)
| Or.inr (Or.inl h) => ?c1
| Or.inr (Or.inr h) => ?c2;
case c2 => apply Or.inl; assumption;
case c1 => apply Or.inr; apply Or.inl; assumption
}
theorem tst6 {p q r} (h : p q r) : r q p:=
by {
match h with
| Or.inl h => exact Or.inr (Or.inr h)
| Or.inr (Or.inl h) => ?c1
| Or.inr (Or.inr h) =>
apply Or.inl;
assumption;
case c1 => apply Or.inr; apply Or.inl; assumption
}
theorem tst7 {p q r} (h : p q r) : r q p:=
by match h with
| Or.inl h =>
exact Or.inr (Or.inr h)
| Or.inr (Or.inl h) =>
apply Or.inr;
apply Or.inl;
assumption
| Or.inr (Or.inr h) =>
apply Or.inl;
assumption
inductive ListLast.{u} {α : Type u} : List α → Type u
| empty : ListLast []
| nonEmpty : (as : List α) → (a : α) → ListLast (as ++ [a])
axiom last {α} (xs : List α) : ListLast xs
axiom back {α} [Inhabited α] (xs : List α) : α
axiom popBack {α} : List α → List α
axiom backEq {α} [Inhabited α] : (xs : List α) → (x : α) → back (xs ++ [x]) = x
axiom popBackEq {α} : (xs : List α) → (x : α) → popBack (xs ++ [x]) = xs
theorem tst8 {α} [Inhabited α] (xs : List α) : xs ≠ [] → xs = popBack xs ++ [back xs] :=
match xs, h:last xs with
| _, ListLast.empty => fun h => absurd rfl h
| _, ListLast.nonEmpty ys y => fun _ => sorry
theorem tst9 {α} [Inhabited α] (xs : List α) : xs ≠ [] → xs = popBack xs ++ [back xs] := by
match xs, h:last xs with
| _, ListLast.empty => intro h; exact absurd rfl h
| _, ListLast.nonEmpty ys y => intro; exact sorry