lean2/tests/lean/unfold.lean

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import data.nat
open nat
definition f (a b : nat) := a + b
example (a b : nat) : f a b = 0 → f b a = 0 :=
begin
intro h,
unfold f at h,
state,
unfold f,
state,
rewrite [add.comm],
exact h
end
example (a b : nat) : f a b = 0 → f b a = 0 :=
begin
intro h,
unfold f at *,
state,
rewrite [add.comm],
exact h
end
example (a b c : nat) : f c c = 0 → f a b = 0 → f b a = f c c :=
begin
intros [h₁, h₂],
unfold f at (h₁, h₂),
state,
unfold f,
rewrite [add.comm, h₁, h₂],
end
example (a b c : nat) : f c c = 0 → f a b = 0 → f b a = f c c :=
begin
intros [h₁, h₂],
unfold f at * ⊢,
state,
unfold f,
rewrite [add.comm, h₁, h₂],
end