∀ {𝕜 : Type u_1} [inst : NontriviallyNormedField 𝕜] {E : Type u_2} [inst_1 : NormedAddCommGroup E]
  [inst_2 : NormedSpace 𝕜 E] {F : Type u_3} [inst_3 : NormedAddCommGroup F] [inst_4 : NormedSpace 𝕜 F] {G : Type u_4}
  [inst_5 : NormedAddCommGroup G] [inst_6 : NormedSpace 𝕜 G] {x : E} {s : Set E} {H : Type u_5}
  [inst_7 : NormedAddCommGroup H] [inst_8 : NormedSpace 𝕜 H] {c : E → G →L[𝕜] H} {d : E → F →L[𝕜] G},
  DifferentiableWithinAt 𝕜 c s x →
    DifferentiableWithinAt 𝕜 d s x → DifferentiableWithinAt 𝕜 (fun y => (c y).comp (d y)) s x