The Swift Compiler and Standard Library

1. The Swift Compiler and the Standard Library Talk at Bangalore Swift Meetup Oct 4 2014 @HasGeek

2. I am Santosh Rajan santoshrajan.com twitter.com/santoshrajan github.com/santoshrajan in.linkedin.com/in/santoshrajan

3. Chris Lattner • Author of LLVM since 2002 • Joined Apple 2005 • Author Of the Swift Language since 2010

4. Low Level Virtual Machine (LLVM) C C++ Objective C ? Low Level Language LLVM Machine Code X86 PowerPC ARM SPARC Other..

5. Problem • C, C++, Objective C too hard for App developers Solution • Simple Language syntax like JavaScript • Static Typing to allow compiler optimisations • Higher order functions to enable closures • Host of other features …

6. Low Level Virtual Machine (LLVM) C C++ Objective C Swift Low Level Language LLVM Machine Code X86 PowerPC ARM SPARC Other..

7. Where is Swift? $ xcrun -f swift /Applications/Xcode.app/Contents/Developer/Toolchains/ XcodeDefault.xctoolchain/usr/bin/swift Set an Alias alias swift=/Applications/Xcode.app/Contents/Developer/ Toolchains/XcodeDefault.xctoolchain/usr/bin/swift

8. REPL $ swift Welcome to Swift! Type :help for assistance. 1> 2 + 2 $R0: Int = 4 2> Run $ echo "println("Hello World")" > hello.swift $ swift hello.swift Hello World

9. Where is the Swift Compiler? $ xcrun -f swiftc /Applications/Xcode.app/Contents/Developer/Toolchains/ XcodeDefault.xctoolchain/usr/bin/swiftc Set an Alias alias swiftc=/Applications/Xcode.app/Contents/ Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ swiftc

10. Compile and Run $ swiftc hello.swift -o hello $ ./hello Hello World Generate LLVM bytecode $ swiftc -emit-bc hello.swift -o hello.bc

11. Command Line Arguments // edit hello.swift to ! dump(Process.arguments) $ swift hello.swift foo bar “hello world” ▿ 4 elements — [0]: hello.swift — [1]: foo — [2]: bar — [3]: hello world

12. Swift Standard Library • Types • Protocols • Operators • Global Functions

13. Types Create Types Using • Enums • Structs • Classes Enums and Struct are value types. Classes are reference Types.

14. Enums Use Enums when the Values of the Type are limited. e.g. Planets. Enum Bit { case Zero case One func Successor() -> Bit func predecessor() -> Bit }

15. Structs All Basic Value Types in Swift are defined using Structs. e.g. Bool, Int, Float, Double, Array, Dictionary. Struct Array<T> { var count: Int { get } var isEmpty: Bool { get } mutating func append(newElement: T) mutating func insert(newElement: T, atIndex i: Int) } Instance Variables Instance Methods

16. Classes Classes are reference Types. Use Classes when instances are Objects.

17. All Types Array AutoreleasingUnsafeMutablePoint er BidirectionalReverseView Bit Bool CFunctionPointer COpaquePointer CVaListPointer Character ClosedInterval CollectionOfOne ContiguousArray Dictionary DictionaryGenerator DictionaryIndex Double EmptyCollection EmptyGenerator EnumerateGenerator EnumerateSequence FilterCollectionView FilterCollectionViewIndex FilterGenerator FilterSequenceView Float Float80 FloatingPointClassification GeneratorOf GeneratorOfOne GeneratorSequence HalfOpenInterval HeapBuffer HeapBufferStorage ImplicitlyUnwrappedOptional IndexingGenerator Int Int16 Int32 Int64 Int8 LazyBidirectionalCollection LazyForwardCollection LazyRandomAccessCollection LazySequence MapCollectionView MapSequenceGenerator MapSequenceView MirrorDisposition ObjectIdentifier OnHeap Optional PermutationGenerator QuickLookObject RandomAccessReverseView Range RangeGenerator RawByte Repeat ReverseBidirectionalIndex ReverseRandomAccessIndex SequenceOf SinkOf Slice StaticString StrideThrough StrideThroughGenerator StrideTo StrideToGenerator String UInt UInt16 UInt32 UInt64 UInt8 UTF16 UTF32 UTF8 UnicodeDecodingResult UnicodeScalar Unmanaged UnsafeBufferPointer UnsafeBufferPointerGenerator UnsafeMutableBufferPointer UnsafeMutablePointer UnsafePointer Zip2 ZipGenerator2

18. Protocols Protocols are templates for Structs and Classes. Like interfaces in Java Any Type that implements the Printable protocol should implement the instance variable `description` which is a getter that returns a String. ! protocol Printable { var description: String { get } }

19. SequenceType Protocol Types implementing this protocol can be used in for loops. e.g. String, Array, Dictionary protocol SequenceType { func generate() -> GeneratorType } GeneratorType Protocol protocol GeneratorType { mutating func next() -> Element? }

20. SequenceType Example var arr = ["Hello", "how", "are", “you"] var generator = arr.generate() while let elem = generator.next() { println(elem) } Is the same as for elem in arr { println(elem) } In fact the swift compiler will will compile the `for loop` into the `while loop` above.

21. All Protocols AbsoluteValuable AnyObject ArrayLiteralConvertible BidirectionalIndexType BitwiseOperationsType BooleanLiteralConvertible BooleanType CVarArgType CollectionType Comparable DebugPrintable DictionaryLiteralConvertib le Equatable ExtendedGraphemeClusterLit eralConvertible ExtensibleCollectionType FloatLiteralConvertible FloatingPointType ForwardIndexType GeneratorType Hashable IntegerArithmeticType IntegerLiteralConvertible IntegerType IntervalType MirrorType MutableCollectionType MutableSliceable NilLiteralConvertible OutputStreamType Printable RandomAccessIndexType RangeReplaceableCollectio nType RawOptionSetType RawRepresentable Reflectable SequenceType SignedIntegerType SignedNumberType SinkType Sliceable Streamable Strideable StringInterpolationConvert ible StringLiteralConvertible UnicodeCodecType UnicodeScalarLiteralConver tible UnsignedIntegerType _ArrayBufferType _BidirectionalIndexType _CocoaStringType _CollectionType _Comparable _ExtensibleCollectionType _ForwardIndexType _Incrementable _IntegerArithmeticType _IntegerType _ObjectiveCBridgeable _RandomAccessIndexType _RawOptionSetType _SequenceType _Sequence_Type _SignedIntegerType _SignedNumberType _Sliceable _Strideable _SwiftNSArrayRequiredOverri desType _SwiftNSArrayType _SwiftNSCopyingType _SwiftNSDictionaryRequiredO verridesType _SwiftNSDictionaryType _SwiftNSEnumeratorType _SwiftNSFastEnumerationType _SwiftNSStringRequiredOverr idesType _SwiftNSStringType _UnsignedIntegerType

22. Operators != !== % %= & &% && &* &+ &- &/ &= * *= + += - -= ... ..< / /= < << <<= <= == === > >= >> >>= ?? ^ ^= | |= || ~= ~> prefix ! prefix + prefix ++ prefix - prefix -- prefix ~ postfix ++ postfix --

23. Global Functions Comes with over 70 Global built in functions. Will cover some here. Printing to an output stream. Default standard out. dump(object) print(object) println(object)

24. assert Takes a condition expression that evaluates to true or false, and a message. // file assert.swift assert(Process.arguments.count > 1, “Argument required”) println(“Argument Supplied”) ! ! $ swift assert.swift // assertion failed: Argument required. $ swift assert.swift foo // Argument Supplied

25. contains Takes a sequence and calls the predicate function with every element. var arr = [“Foo”, “Bar”, “Baz”, “Bez”] if contains(arr, {$0 == “Baz”}) { println(“Array contains Baz”) }

26. enumerate Returns an EnumerateGenerater. The Generator returns a tuple containing index and Element. var intarray = [1, 2, 3, 4] for (index, element) in enumerate(intarray) { println(“Item (index): (element)”) }

27. map func square(x: Int) -> Int { return x * x } var num: Int? = 10 println(map(num, square)) // prints Optional(100) wut? // Haskells fmap for optionals func map<T, U>(x: T?, f: (T) -> U) -> U?

28. map (overloaded) func square(x: Int) -> Int { return x * x } let mappedArray = map([1, 2, 3, 4, 5], square) // mappedArray is [1, 4, 9, 16, 25] // Definitions func map<C : CollectionType, T> (source: C, transform: (C.Generator.Element) -> T) -> [T] func map<S : SequenceType, T> (source: S, transform: (S.Generator.Element) -> T) -> [T]

29. stride for x in stride(from: 0, through: 100, by: 10) { println(x) } // 0, 10, 20, 30, 40, 50, 60 , 70, 80, 90, 100 ! ! for x in stride(from: 100, through: 0, by: -10) { println(x) } //100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 0

30. All Global Functions abs advance alignof alignofValue assert assertionFailure contains count countElements debugPrint debugPrintln distance dropFirst dropLast dump enumerate equal extend fatalError filter find first getVaList indices insert isEmpty join last lazy lexicographicalCompare map max maxElement min minElement numericCast overlaps partition precondition preconditionFailure prefix print println reduce reflect removeAll removeAtIndex removeLast removeRange reverse sizeof sizeofValue sort sorted splice split startsWith stride strideof strideofValue suffix swap toDebugString toString transcode underestimateCount unsafeAddressOf unsafeBitCast unsafeDowncast withExtendedLifetime withUnsafeMutablePointer withUnsafeMutablePointer s withUnsafePointer withUnsafePointers withVaList

31. References Auto Generated Docs - Swifter Airspeed Velocity- swift standard library

The Swift Compiler and Standard Library

The Swift Compiler and Standard Library

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