OMG, just yesterday I wrote a comment saying that I regret not learning K (I instead chose J) due to being too hung up on the notion of free software at the time... What a coincidence! Now I have no excuses anymore, time to learn K!
K specializes in financial data, i.e. lists of 1d arrays. Other APLs, and J, are more high-dimensional math oriented and specialize in true multidimensional arrays.
