∀ {𝕜 : Type u} [inst : NontriviallyNormedField 𝕜] {F : Type v} [inst_1 : NormedAddCommGroup F]
  [inst_2 : NormedSpace 𝕜 F] {f : 𝕜 → F} {f' : F} {x : 𝕜} {L : Filter 𝕜},
  HasDerivAtFilter f f' (L ×ˢ pure x) ↔ Filter.Tendsto (slope f x) (L ⊓ Filter.principal {x}ᶜ) (nhds f')