lean4-htt/tests/lean/run/derivingNonempty.lean
2022-12-22 03:48:15 +01:00

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inductive Foo (α : Type u) (β : Type v) where
| mk₁ : α → Foo α β
| mk₂ : List β → Foo α β
deriving instance Nonempty for Foo
def ex1 [Nonempty α] : Nonempty (Foo α β) :=
inferInstance
inductive Bla (α : Type u) (β : Type v) where
| mk₁ : α → Bla α β
| mk₂ : β → Bla α β
deriving instance Nonempty for Bla
def ex2 [Nonempty α] : Nonempty (Bla α β) :=
inferInstance
structure Point (α : Type) where
x : α
y : α
deriving Nonempty
def ex3 [Nonempty α] : Nonempty (Point α) :=
inferInstance
inductive Lst (α : Type) where
| nil
| cons : α → Lst α → Lst α
deriving Nonempty
def ex4 : Nonempty (Lst α) :=
inferInstance
mutual
inductive FooLst (α : Type) where
| nil
| cons : Boo α → FooLst α → FooLst α
deriving Nonempty
inductive Boo (α : Type) where
| node : FooLst α → Boo α
deriving Nonempty
end
def ex5 : Nonempty (Boo α) :=
inferInstance