fast case for tuple

Author: oxinabox

src/stage1/forward.jl

@@ -257,6 +257,10 @@ function (::∂☆{N})(f::ATB{N, typeof(tuple)}, args::AbstractTangentBundle{N}.
     ∂vararg{N}()(args...)
 end
 
+function (::∂☆{N})(f::ATB{N, typeof(tuple)}, args::ZeroBundle{N}...) where {N}
+    ZeroBundle{N}(map(primal, args))  # special fast case
+end
+
 struct FwdMap{N, T<:AbstractTangentBundle{N}}
     f::T
 end