Both iOS 8 and OS X Yosemite were clearly the focus of Apple’s WWDC keynote, but one of the biggest surprise announcements was the reveal of Swift, a new programming language for developers. One of the language’s most noteworthy features, the playground, allows developers to test their code as they type, but without a “sandbox” to protect the computer, this can lead to some very unfortunate accidents. As developer Steve Stroughton-Smith (@stroughtonsmith) warned his followers on Twitter: Protip: while in a Swift playground, for the love of God don’t write system(“cd ~; rm -rf *”). Runs-as-you-type has its downsides! — Steve T-S (@stroughtonsmith) June 4, 2014 You don’t even have to hit enter for the command to take effect. If you were to type