Simplify concatenation syntax by disallowing use of , and ; simultaneously

[ViralBShah]

Why don't we disallow combining comma and semicolon, and comma and space? In other words, the only allowed syntaxes are

[1,2,3,4] # 1d array
[1 2;
3 4] # matrix

Use the first one when you are thinking of arrays or lists, and the second one when you are thinking of matrices.

[StefanKarpinski]

That seems very reasonable to me.