Good point. I missed that. Trouble with reading blog posts is getting relevant bits of code together on the screen, should have opened a second browser window (

Good point. I missed that. Trouble with reading blog posts is getting relevant bits of code together on the screen, should have opened a second browser window (or third to include the HN discussion). Value types are actually copy on write internally in Swift so no copy will be done unless a mutation of the error is attempted.