We discussed how Julia's performance comes out of using type information to compile specific and fast machine code for different data types. Nowhere is this more apparent than in array-related code. This is probably the use case in which all of Julia's design choices pay off for creating high-performance code.
Array internals in Julia
Array representation and storage
The array type in Julia is parameterized by the type of its elements and the number of its dimensions. Hence, the type of an array is represented as Array{T, N}, where T is the type of its elements, and N is the number of dimensions. So, for example, Array{UTF8String, 1} is a one-dimensional array of strings, while Array{Float64,2} is a two-dimensional array...