no goals
ι : Type ?u.88
α : Type u
β : Type v
γ : Type w
inst✝¹ : PseudoMetricSpace α
inst✝ : PseudoMetricSpace β
f : α → β
⊢ Isometry f ↔ ∀ (x y : α), nndist (f x) (f y) = nndist x y
simp only [Isometry, edist_nndist, ENNReal.coe_eq_coe]