From what I understand, J has a lot of problems with efficient implementation because array ranks (multi-dimensional arrays) influence how operations are carrie

From what I understand, J has a lot of problems with efficient implementation because array ranks (multi-dimensional arrays) influence how operations are carried out (http://jsoftware.com/help/learning/07.htm http://jsoftware.com/help/learning/07.htm), and the ranks are not known in advance. [ranks also have horribly complicated semantics: http://www.jsoftware.com/papers/rank1.htm http://www.jsoftware.com/papers/rank1.htm] K doesn't have this problem because it only has vectors.