lean2/tests/lean/run/eq6.lean

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import data.list
open list
definition append {A : Type} : list A → list A → list A
| append nil l := l
| append (h :: t) l := h :: (append t l)
theorem append_nil {A : Type} (l : list A) : append nil l = l :=
rfl
theorem append_cons {A : Type} (h : A) (t l : list A) : append (h :: t) l = h :: (append t l) :=
rfl
example : append ((1:nat) :: 2 :: nil) (3 :: 4 :: 5 :: nil) = (1 :: 2 :: 3 :: 4 :: 5 :: nil) :=
rfl