これは熱い。ﾒｺﾒｺ省略できる
http://qiita.com/uasi/items/0a72bb444002471d832f

let sorted = sort(anArray, { (s1: String, s2: String) -> Bool in
return s1 < s2
})
↓
let sorted = sort(anArray, { s1, s2 in
return s1 < s2
})
↓
let sorted = sort(anArray, { s1, s2 in s1 < s2 })
↓
let sorted = sort(anArray, { $0 < $1 })
↓
let sorted = sort(anArray, <)