[iOS Conf SG 2016] A Toy Web Framework in Swift

A talk using various parts of a web framework implementation to talk about a few Swift features — what they can do, and what they can't do (yet).

Transcript

1. A Toy Web Framework in Swift Boon
2. Why a Web Framework? • I've never built one • Well-known domain • The basic premise is simple
3. What is a Web (Application) Framework? • Routing • Presentation • Logic • Persistence • Testing
4. Blamework
5. • Routing • Presentation • Logic • Persistence • Testing
8. Prototype with Swift Playgrounds
10. GCDWebServer
11. Wiring up GCDWebServer let response = appServer.process(request: Request(verb: req.method!, path: req.path, query: req.query, form: req.arguments)) return GCDWebServerDataResponse(html: response)
13. Routing get '/hobbies' do 'Return the HTML for a list of hobbies here' end post '/hobbies/new' do #Create a new hobby and redirect to GET end
14. Vapor drop.get("welcome") { request in return "Hello" } — h$ps://vapor.github.io/documenta8on/rou8ng/basic.html
15. Perfect api2Routes.add(method: .get, uri: "/call2", handler: { _, response in response.setBody(string: "API v2 CALL 2") response.completed() }) — h$ps://github.com/PerfectlySo9/PerfectExample-URLRouAng
16. Routing let routes: [String: Component] = "/something": someComponent, "/anotherPath": anotherComponent, "*": mainComponent] let appServer = BlameworkAppServer(routes: routes)
17. Routing let component = routes[request.path] ?? routes["*"]! return component.renderFor(request: request)
18. Presentation
21. html.head { html.title("Blamework demo") } html.body { html in html.p("My TODO list for today:") html.form { html in html.textField("item") html.submit("Add Item") } html.ol { html in for e in items { html.li(e) } } }
22. A domain-specific language (DSL) is a computer language specialized to a particular application domain. — h$ps://en.wikipedia.org/wiki/Domain-specific_language
23. Swift vs. Ruby
24. html.head { html.title("Blamework demo") } html.body { html in html.p("My TODO...:") html.form { html in html.textField("item") html.submit("Add Item") } html.ol { html in for e in items { html.li(e) } } }
25. @discardableResult public func body( _ string: String) -> String { return tag(name: "body", string: string) } @discardableResult public func body( block: (_ writer: HTMLWriter)->()) -> String { return tag(name: "body", block: block) }
26. @discardableResult public func tag( name: String, attributes: [String:String]=[String:String](), block: (_ writer: HTMLWriter)->()) -> String { let w = self.childWriter() let attr = attributesToString(attributes: attributes) w.name = "\(name)'s" w.string("<\(name) \(attr)>") w.string(block) w.string("</\(name)>") return w.toString() }
27. @discardableResult public func tag( name: String, attributes: [String:String]=[String:String](), string: String) -> String { let w = self.childWriter() let attr = attributesToString(attributes: attributes) w.name = "\(name)'s" w.string("<\(name) \(attr)>") w.string(string) w.string("</\(name)>") return w.toString() }
28. @discardableResult public func body( _ string: String) -> String { return tag(name: "body", string: string) } @discardableResult public func body( block: (_ writer: HTMLWriter)->()) -> String { return tag(name: "body", block: block) }
29. map([!, ", #], cook) => [$, %, &] filter([$, %, &], isVegetarian) => [$, &] reduce([$, &], eat) => ' — h$ps://twi$er.com/steveluscher/status/741089564329054208
30. Persistence
31. Prevayler
32. Premise 1: Structs
33. Premise 2: Protocols
34. Premise 3: Minimal code
35. Only collections and primitive types
36. struct Address { var line1: String var line2: String var zipCode: Int }
37. var addresses = [ Address(line1: "Block 123", line2: "Tampines Street 33", zipCode: "523123"), Address(line1: "20", line2: "Maryland Road", zipCode: "567800")] addresses.write(to: "/path/to/somewhere")
38. struct Address { var line1: String var line2: String var zipCode: Int func toDictionary() -> [String:Any] { return ["line1": line1, "line2": line2, "zipCode: zipCode"] } }
39. Protocols + Default Implementations protocol PersistentObject { func toDictionary() -> [String: Any] }
40. extension PersistentObject { func toDictionary() -> [String:Any] { let result = gen(value: self) if let result = result as? [String:Any] { return result } else { return [String:Any]() } } func gen(value: Any) -> Any {//...} }
41. Reflection + Mirror func gen(value: Any) -> Any { let m = Mirror(reflecting: value) if m.displayStyle == .struct { var result = [String:Any]() for case let (label?, value) in m.children { result[label] = gen(value: value) } return result } else { return value } }
42. extension Array where Element: PersistentObject { func write(to: String) -> Bool { let array = map {$0.toDictionary()} as NSArray return array.write(to: URL(fileURLWithPath: to), atomically: true) } } extension Dictionary where Value: PersistentObject { func write(to: String) -> Bool { var dict = [Key:[String:Any]]() for (k, v) in self { dict[k] = v.toDictionary() } let dict2 = dict as NSDictionary return dict2.write(to: URL(fileURLWithPath: to), atomically: true) } }
43. struct Address { var line1: String var line2: String var zipCode: Int }
44. var addresses = [ Address(line1: "Block 123", line2: "Tampines Street 33", zipCode: "523123"), Address(line1: "20", line2: "Maryland Road", zipCode: "567800")] addresses.write(to: "/path/to/somewhere")
45. struct Address: PersistentObject { var line1: String var line2: String var zipCode: Int }
46. print(items) [Item(title: "Item 1", age: 10, address: Address(value: "address 1")), Item(title: "Item 2", age: 10, address: Address(value: "address 1"))]
47. [Item(title: "Item 1", age: 10, address: Address(value: "address 1")), Item(title: "Item 2", age: 10, address: Address(value: "address 1"))]
48. dump(items) ▿ 2 elements ▿ Item - title: "Item 1" - age: 10 ▿ address: Address - value: "address 1" ▿ Item - title: "Item 2" - age: 10 ▿ address: Address - value: "address 1"
49. func gen(value: Any) -> Any { let m = Mirror(reflecting: value) if m.displayStyle == .struct { var result = [String:Any]() for case let (label?, value) in m.children { result[label] = gen(value: value) } return result } else { return value } }
50. for case let (label?, value) in m.children { result[label] = gen(value: value) }
51. var nums: [Int?] = [1, 2, 3, nil, 5] for e in nums { print("Value: ", e) } Value: Optional(1) Value: Optional(2) Value: Optional(3) Value: nil Value: Optional(5)
52. var nums: [Int?] = [1, 2, 3, nil, 5] for case let e? in nums { print("Value: ", e) } Value: 1 Value: 2 Value: 3 Value: 5
53. let l2 = [[1, 2], [3, 4, 5]].flatMap {$0} l2 // == [1, 2, 3, 4, 5]
54. var nums: [Int?] = [1, 2, 3, nil, 5] for case let e? in nums { print("Value: ", e) } for e in nums.flatMap({$0}) { print("Value: ", e) } Value: 1 Value: 2 Value: 3 Value: 5
55. Javascript
56. let routes: [String: Component] = ["/scripts/turbolinks.js": FileComponent(path: "/path/to/turbolinks.js"), //... ]
57. html.head { html in html.title("Blamework demo") html.script(src: "/scripts/turbolinks.js") }
58. More
59. extension Array where Element: PersistentObject { func write(to: String) -> Bool { let array = map {$0.toDictionary()} as NSArray return array.write(to: URL(fileURLWithPath: to), atomically: true) } }
60. extension Collection where Iterator.Element: PersistentObject { } extension Collection where Iterator.Element == PersistentObject { }
61. extension Collection where Iterator.Element: PersistentObject { } // var list: [PersistentObject] // this is NOT what I want ^ extension Collection where Iterator.Element == PersistentObject { } // var list: [SomeTypeThatImplementsPersistentObject] //e.g // var list: [Addresses] // this is what I want for PersistentObject^
62. Reflection Smoke + Mirrors extension PersistentObject { func toDictionary() -> [String:Any] {} //... } extension Array where Element: PersistentObject {//...} extension Dictionary where Value: PersistentObject {//...}
63. Pattern Matching
64. Fibonacci Sequence 0, 1, 1, 2, 3, 5, 8, 13, 21, ...
65. for e in 0...6 { print("Seq \(e): \(fib(e))") } Seq 0: [0] Seq 1: [0, 1] Seq 2: [0, 1, 1] Seq 3: [0, 1, 1, 2] Seq 4: [0, 1, 1, 2, 3] Seq 5: [0, 1, 1, 2, 3, 5] Seq 6: [0, 1, 1, 2, 3, 5, 8]
66. //0, 1, 1, 2, 3, 5, 8, 13, 21, ... func fib(_ i: Int) -> [Int] { if i == 0 { return [0] } else if i == 1 { return [0, 1] } else { let seq = fib(i-1) let c = seq.count let next = [seq[c-2] + seq[c-1]] return seq + next } }
67. #0, 1, 1, 2, 3, 5, 8, 13, 21, ... def fib(0) do [0] end def fib(1) do [1, 0] end def fib(n) do [x, y | rest] = fib(n-1) [x+y, x, y | rest] end
68. Swift is a Young Language
69. • GCDWebServer https://github.com/swisspol/GCDWebServer • Vapor https://vapor.github.io/documentation/routing/basic.html • Perfect https://github.com/PerfectlySoft/PerfectExample- URLRouting • Pharo/Smalltalk http://pharo.org • Seaside http://www.seaside.st • Elixir http://elixir-lang.org
70. Thank You Follow @hboon