Swift: The new half-range operator

In Xcode beta 3, Swift’s half-closed range operator has changed from .. to ..<, adding a less-than-sign visually distinguish half ranges (up to but not including) from full ones (up to and including). The update enhances visual inspection, making a clear differentiation between half (..<) and full (…) ranges.

While I applaud the intent, I dislike the result.

I get how errors similar to those between assignment and equality operators (= and ==) might happen. But while the =/== operators act in distinct ways, the range operators are more closely related. They’re less likely to produce foundational mistakes, and easier to catch through normal inspection.

A few additional points:

  • The new half range operator is ugly. It turns an elegant for i in 1..5 into a visually confusing 1..<5
  • When used next to a 3-digit, it looks like ascii art: for i in 1..<3 println(“Love you!”)
  • Even without 3-adjacency, the new operator looks like an upside down deranged duck ..<
  • The new operator requires explicit escaping on the web. (Thanks Andrew Wagner)

I’ve filed a radar. If you feel the same, consider adding one too.

As a final note, while this language tweak looks a bit like a literal duck, some are comparing it to the Coding Horror metaphorical one.


  • But you’ve got to admit the old .. vs … was a readability problem.

    I’ve been reading the swift guide and readability is probably my biggest concern. Glad to see they’re working on that. Even if this one isn’t quite there yet…

  • It’s ugly but who cares. If it bothers you just use the range operator. It’s just syntax.

  • Just got onto the tutorials and this change got me. I must admit that while the two dots were more pleasing to look at than the new “..<" , I was kind of hoping that if we're going to go this route why not also have a version "<.." and "<..<"….. oh well