In the early beta release of Swift 0.x, they used x..y for half-open ranges and x...y for closed ranges. This confused people (especially since Ruby already use

In the early beta release of Swift 0.x, they used x..y for half-open ranges and x...y for closed ranges. This confused people (especially since Ruby already used the same operators but the other way around), so they changed the half-open operator to x..<y.