[DNF2]

The semicolon use is actually completely consistent, ";", ";;", ";;;" etc. do indeed refer to incrementation of the corresponding dimension. Try [1;2;3], then [1;2;3 ;; 4;5;6] and then [1;2;3 ;; 4;5;6 ;;; 7;8;9;; 10;11;12]

The confusion arises because "," and whitespace also have overlapping meanings in array notation. "," is used for regular vector creation, and whitespace for concatenation in the second dimension. The coexistence of those two different notations is a bit uneasy, but I doubt that "," and whitespace will be deprecated, since they are so entrenched and familiar. And for 1D and 2D arrays (which probably make up >99% of all literal array use) it's also more elegant and clean.

Maybe this will help: "," separators only work for 1D arrays, you cannot use them while making 2D or higher arrays. Whitespace is used when you want to create the array writing the data down row-wise, so your innermost dimension in writing is actually the second dimension of the array. The semicolons are for completely consistently going from the first to the n'th dimension, with the corresponding number of ";" in each dimension.

I think it would be hard to come up with a nice way to express these in a unified notation.

The way numpy does this with lots of brackets isn't really very convenient when working in 2D, which is the more common case.