Reductions along dimension for tuples

The title suites my report, so I made a reply here. Should I expect an ERROR for the 2nd function call as the 4th? I don’t get the sense of the return value of the 2nd. (Version 0.7.0-DEV.1816 (2017-09-17 15:48 UTC))

julia> mean([1 2])

julia> mean([1 2], [3 4])
1×2 Array{Float64,2}:
 1.0  2.0

julia> mean((1, 2))

julia> mean((1, 2), (3, 4))
ERROR: MethodError: no method matching mean(::Tuple{Int64,Int64}, ::Tuple{Int64,Int64})
Closest candidates are:
  mean(::Union{Function, Type}, ::Any) at statistics.jl:19
  mean(::AbstractArray{T,N} where N, ::Any) where T at statistics.jl:75
  mean(::Any) at statistics.jl:34

mean([1 2], [3 4]) calls mean(v[, region]). See ?mean.

(and no, this has nothing to do with the original question of this topic)

I’ve split this into a new topic.