I started with @v{1,3} = (...) and a separate computation of $v[0] and $v[2]. But I turned that into @v{0,1,2,3} = (...), where the slice on @v is not only useless, but also incorrect now that I think of it (since it was actually a slice on %v). And yes the code can be shorter (there is a lot of unnecessary white space for example), but I was expecting TJCooper to adapt the oneliner to his needs anyway.