>No multiplication by juxtaposition

That's possible albeit limited.

  julia> x=[1,2]
  2-element Array{Int64,1}:
   1
   2

  julia> 2x
  2-element Array{Int64,1}:
   2
   4

  julia> 2(x+x)
  2-element Array{Int64,1}:
   4
   8

  julia> x=2
  2

  julia> [1,2]x
  2-element Array{Int64,1}:
   2
   4

but, as mentioned, due to element access the inverse (x[1,2]) cannot work. Neither can multiply variables that way.