dropFirst for any SequenceType

dropFirst.swift

func myDropFirst<S: SequenceType>(seq: S) -> SequenceOf<S.Generator.Element> {
    return SequenceOf { ()->GeneratorOf<S.Generator.Element> in
        var g = seq.generate()
        let first = g.next()
        // if you prefer your dropFirst to explodinate on empty
        // sequences, add an assert(first != nil) here...
        return GeneratorOf {
            // shouldn't call GeneratorType.next()
            // after it's returned nil the first time
            first == nil ? nil : g.next()
        }
    }
}

let s = myDropFirst(1...5)

for x in s {
    println(x)
}