Well I prefer the first two, although i would just use normal concatenation instead of the @{[]} (especially as its actually a char shorter :-), and i would put the for on the following line. The third example is interesting, I would probably go with your second implementation, but I can see the point you are making. Overall however I would say that the readability differences are so minimal that I would go for the more efficient of the statements. I know that folks get their knickers in a knot about premature optimisation, but I don't think is such a case.