lean4-htt/tests/lean/run/match1.lean
2020-09-04 18:22:56 -07:00

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new_frontend
def f (xs : List Nat) : List Bool :=
xs.map fun
| 0 => true
| _ => false
#eval f [1, 2, 0, 2]
theorem ex1 : f [1, 0, 2] = [false, true, false] :=
rfl
#check f
def g (xs : List Nat) : List Bool :=
xs.map $ by {
intro
| 0 => exact true
| _ => exact false
}
theorem ex2 : g [1, 0, 2] = [false, true, false] :=
rfl
theorem ex3 {p q r : Prop} : p q → r → (q ∧ r) (p ∧ r) :=
by intro
| Or.inl hp, h => { apply Or.inr; apply And.intro; assumption; assumption }
| Or.inr hq, h => { apply Or.inl; exact ⟨hq, h⟩ }