I was talking about pure arrays of bits, as a theoretical construct, but you are right to notice that if not all your arrays are the same length, then each arra

I was talking about pure arrays of bits, as a theoretical construct, but you are right to notice that if not all your arrays are the same length, then each array needs to specify a length. 64-bit integers are like bit-arrays where each array is pre-defined to be 64-bits long and therefore doesn't need to store its length. You could define all your bit arrays to be 8 bytes long each and accomplish the same thing. Your better tact at shooting holes in the bit-array approach is not from memory consumption (you loose on those grounds), but you from a 'performance' standpoint, you can make the case the integer comparisons all take one clock cycle, and operations on bit-arrays are slower, because you have to check each bit individually to do logic. Summary: For storage size, bit-arrays win, and for performance integers win. So based on system needs you'd choose a solution, weighing the pros/cons.