What you&#x27;re seeing here is a result of an unfortunate interaction with bridging to C APIs. fd_set is a C struct which contains a fixed-length array. Swift doesn&#x27;t have fixed-length arrays, so those get translated to tuples instead.<p>This is not ideal, but it comes up almost never.<p>As for your suggestion, that seems like an entirely stylistic thing. DRY is about not copy&#x2F;pasting large chunks of code, not minimizing individual lines by using compound mutate&#x2F;assign operators. I&#x27;ve never seen anyone say (before!) that something like `x = x + 1` violates DRY.