lean2/tests/lean/run/eq16.lean

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import data.list
open list
variable {A : Type}
set_option pp.implicit true
definition append : list A → list A → list A,
append nil l := l,
append (h :: t) l := h :: (append t l)
theorem append_nil (l : list A) : append nil l = l :=
rfl
theorem append_cons (h : A) (t l : list A) : append (h :: t) l = h :: (append t l) :=
rfl
example : append (1 :: 2 :: nil) (3 :: 4 :: 5 :: nil) = (1 :: 2 :: 3 :: 4 :: 5 :: nil) :=
rfl