First commit

Contents.swift

+import UIKit
+
+class Singleton {
+    var data: String
+    init(autoClosure: @autoclosure () -> String){
+        data = autoClosure()
+    }
+    
+    static var shared: Singleton = Singleton(autoClosure: {"autoclosed singleton"}())
+}
+
+Singleton.shared.data
+
+extension Sequence where Element == Int {
+    func double() -> [Int]{
+        return self.map() {$0 * 2}
+    }
+}
+extension Sequence where Element == Double {
+    func double() -> [Double] {
+        return self.map() {$0 * 2}
+    }
+}
+extension Sequence where Element == String {
+    func double() -> [String] {
+        return self.map() {String((Double($0) ?? 0) * 2)}
+    }
+}
+
+print([1,2,3,4].double())
+print([1.1,2.2,3.3,4.4].double())
+print(["1.1","2.2","3.3","4.4"].double())

contents.xcplayground

+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<playground version='5.0' target-platform='ios' buildActiveScheme='true' importAppTypes='true'>
+    <timeline fileName='timeline.xctimeline'/>
+</playground>
\ No newline at end of file

playground.xcworkspace/contents.xcworkspacedata

+<?xml version="1.0" encoding="UTF-8"?>
+<Workspace
+   version = "1.0">
+   <FileRef
+      location = "group:">
+   </FileRef>
+</Workspace>

timeline.xctimeline

+<?xml version="1.0" encoding="UTF-8"?>
+<Timeline
+   version = "3.0">
+   <TimelineItems>
+   </TimelineItems>
+</Timeline>

xcuserdata/Jon.xcuserdatad/xcschemes/xcschememanagement.plist

+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>SchemeUserState</key>
+	<dict>
+		<key>protocol (Playground).xcscheme</key>
+		<dict>
+			<key>isShown</key>
+			<false/>
+			<key>orderHint</key>
+			<integer>0</integer>
+		</dict>
+	</dict>
+</dict>
+</plist>