Beyond Kotlin - Advanced features for API Makers

Kotlin talk for experimented developers

Transcript

1. Beyond Kotlin Advanced features for API makers
2. Work @ ekito Mobile & Cloud Kotlin Lover @arnogiu Arnaud GIULIANI medium.com/@giuliani.arnaud/ ekito.fr/people #DevFestToulouse
5. Statically typed programming language for modern multiplatform applications
7. Kotlin on Android, now official
8. h5ps:/ /spring.io/blog/2017/01/04/introducing-kotlin-support-in-spring- framework-5-0 h5p:/ /www.javamagazine.mozaicreader.com/ #&pageSet=5&page=0&contentItem=0 (March/ April 2017) h5ps:/ /www.thoughtworks.com/radar/languages-and-frameworks/kotlin
9. h5ps:/ /zeroturnaround.com/rebellabs/developer-producNvity-report-2017-why-do-you-use-java-tools-you-use/
11. Many well-known companies are using Kotlin: Pinterest, Coursera, NeUlix, Uber, Square, Trello, Basecamp, amongst others well-known banks (such as Goldman Sachs, Wells Fargo, J.P. Morgan, Deutsche Bank, UBS, HSBC, BNP Paribas, Société Générale)
13. KOTLIN is not just a syntactic sugar It’s all about writing SAFER & BETTER APPS !
14. val / var Null safety Class / Object Lambda Functions Data Class Properties & delegates Default Values Named Parameters Extension Functions InterOp Not today!
16. Let’s take a concrete context
17. // A Bean Definition data class BeanDefinition(val name: String, val clazz: KClass<*>) like dependency injection An advanced API development use case Let’s take
18. Before, we need some APIs ⚒
19. Writing Lambda APIs
20. // A Bean definition val beanDef: BeanDefinition? // let beanDef?.let { println("bean name is '${it.name}'") } // let & assign value val complexName: String? = beanDef?.let { "name : ${it.name} & class ${it.clazz}" } Safely executing with let // A Bean definition val beanDef: BeanDefinition? // let beanDef?.let { println("bean name is '${it.name}'") }
21. // takeIf (validate predicate) val bean = beanDef?.takeIf { it.name.isNotEmpty() } val bean = beanDef?.takeUnless { it.name.isNullOrEmpty() } // A Bean definition val beanDef: BeanDefinition? = ... // Guard like expression val bean: BeanDefinition = beanDef?.takeIf { it.name.isNotEmpty() } ?: error("bean name is empty") // Guard like expression val bean: BeanDefinition = beanDef?.takeIf { it.name.isNotEmpty() } ?: error("bean name is empty") val bean: BeanDefinition = beanDef?.takeIf { it.name.isNotEmpty() } ?: return // takeIf (validate predicate) val bean = beanDef?.takeIf { it.name.isNotEmpty() } val bean = beanDef?.takeUnless { it.name.isNullOrEmpty() } takeIf & takeUnless // A Bean definition val beanDef: BeanDefinition? = ...
22. let ~ run -> return last value also ~ apply -> return itself with() -> function & return last value it let ~ run -> return last value also ~ apply -> return itself with() -> function & return last value this
23. Encapsulate behavior for a target object
24. Lambda function Receiver Type fun T.function( (T) -> R) fun T.function( T.() -> R) Writing encapsulation public inline fun <T> T.apply(block: T.() -> Unit): T { block(); return this } public inline fun <T> T.also(block: (T) -> Unit): T { block(this); return this } public inline fun <T> T.apply(block: T.() -> Unit): T { block(); return this } public inline fun <T> T.also(block: (T) -> Unit): T { block(this); return this } public inline fun <T> T.apply(block: T.() -> Unit): T { block(); return this } public inline fun <T> T.also(block: (T) -> Unit): T { block(this); return this } public inline fun <T> T.apply(block: T.() -> Unit): T { block(); return this } public inline fun <T> T.also(block: (T) -> Unit): T { block(this); return this }
25. SAM Conversion public class JavaBeanDefinition { String name; Class clazz; public JavaBeanDefinition(String name, Class clazz) {...} public void postInit(JavaInitializingBean initBean){ // Register post init } } public interface JavaInitializingBean { void onInitDone(); } val clazz = MyService::class.java val javaBean = JavaBeanDefinition(clazz.simpleName,clazz) public class JavaBeanDefinition { String name; Class clazz; public JavaBeanDefinition(String name, Class clazz) {...} public void postInit(JavaInitializingBean initBean){ // Register post init } } public interface JavaInitializingBean { void onInitDone(); } val clazz = MyService::class.java val javaBean = JavaBeanDefinition(clazz.simpleName,clazz) javaBean.postInit { println("bean has been defined ! ") } JAVA JAVA
26. The functional way // A Bean definition with post init data class BeanDefinition(val name: String, val clazz: KClass<*>) { fun postInit(initializingBean: InitializingBean) { // register post init ... } } // A Bean definition with post init data class BeanDefinition(val name: String, val clazz: KClass<*>) { fun postInit(initializingBean: () -> Unit) { // register post init ... } } val clazz = MyService::class val bean = BeanDefinition(clazz.java.simpleName, clazz) val clazz = MyService::class val bean = BeanDefinition(clazz.java.simpleName, clazz) bean.postInit { println("bean has been defined ! ") }
27. Types
28. Types Hierarchy
29. Types Hierarchy (again) ? ?
30. Dealing with generics sealed class BeanDefinition(val name : String, val clazz : KClass<*>) class Singleton(n : String, c : KClass<*>) : BeanDefinition(n,c) class Factory(n : String, c : KClass<*>) : BeanDefinition(n,c) fun <T> registerBean(def: T) { //... } // Limit with Bounds fun <T : BeanDefinition> registerBean(def: T) { //... }
31. Dealing with generics sealed class BeanDefinition(val name : String, val clazz : KClass<*>) class Singleton(n : String, c : KClass<*>) : BeanDefinition(n,c) class Factory(n : String, c : KClass<*>) : BeanDefinition(n,c) fun <T> registerBean(def: T) { //... } class BeanProvider<T : BeanDefinition> { } // Limit with Bounds fun <T : BeanDefinition> registerBean(def: T) { //... } // Limit with Bounds fun <T : BeanDefinition> registerBean(def: T) { //... } sealed class BeanDefinition(val name : String, val clazz : KClass<*>) class Singleton(n : String, c : KClass<*>) : BeanDefinition(n,c) class Factory(n : String, c : KClass<*>) : BeanDefinition(n,c)
32. Reified Types fun declareBean(name :String, clazz : KClass<*>){ val bean = BeanDefinition(name,clazz) }
33. Reified Types fun declareBean(name :String, clazz : KClass<*>){ val bean = BeanDefinition(name,clazz) } fun <T> declareBean(name :String, clazz : T){ val bean = BeanDefinition(name,???) } fun <T> declareBean(name :String, clazz : T){ // Capture Type parameter class val clazz = T::class val bean = BeanDefinition(name,clazz) }
34. Reified Types fun declareBean(name :String, clazz : KClass<*>){ val bean = BeanDefinition(name,clazz) } fun <T> declareBean(name :String, clazz : T){ val bean = BeanDefinition(name,???) } fun <T> declareBean(name :String, clazz : T){ // Capture Type parameter class val clazz = T::class val bean = BeanDefinition(name,clazz) } inline fun <reified T> declareBean(name :String, clazz : T){ // Capture Type parameter class val clazz = T::class val bean = BeanDefinition(name,clazz) }
35. Reified Types fun declareBean(name :String, clazz : KClass<*>){ val bean = BeanDefinition(name,clazz) } fun <T> declareBean(name :String, clazz : T){ val bean = BeanDefinition(name,???) } fun <T> declareBean(name :String, clazz : T){ // Capture Type parameter class val clazz = T::class val bean = BeanDefinition(name,clazz) } inline fun <reified T> declareBean(name :String, clazz : T){ // Capture Type parameter class val clazz = T::class val bean = BeanDefinition(name,clazz) } inline fun <reified T> declareBean(){ // Capture Type parameter class val clazz = T::class val name = clazz.simpleName ?: "" val bean = BeanDefinition(name,clazz) }
36. Reified Types fun declareBean(name :String, clazz : KClass<*>){ val bean = BeanDefinition(name,clazz) } fun <T> declareBean(name :String, clazz : T){ val bean = BeanDefinition(name,???) } fun <T> declareBean(name :String, clazz : T){ // Capture Type parameter class val clazz = T::class val bean = BeanDefinition(name,clazz) } inline fun <reified T> declareBean(name :String, clazz : T){ // Capture Type parameter class val clazz = T::class val bean = BeanDefinition(name,clazz) } inline fun <reified T> declareBean(){ // Capture Type parameter class val clazz = T::class val name = clazz.simpleName ?: "" val bean = BeanDefinition(name,clazz) } inline fun <reified T> declareBean(){ // Capture Type parameter class val clazz = T::class val name = clazz.simpleName ?: "" val bean = BeanDefinition(name,clazz) } declareBean<MyService>()
37. Type Aliases typealias BeanList = List<BeanDefinition> typealias BeanList = List<BeanDefinition> val list : BeanList = listOf()
38. Type Aliases typealias BeanList = List<BeanDefinition> typealias BeanList = List<BeanDefinition> val list : BeanList = listOf() typealias BeanValidator = (BeanDefinition) -> Boolean typealias BeanList = List<BeanDefinition> val list : BeanList = listOf() typealias BeanValidator = (BeanDefinition) -> Boolean val bv : BeanValidator = { def -> def.name.isNotEmpty()}
39. Type Aliases typealias BeanList = List<BeanDefinition> typealias BeanList = List<BeanDefinition> val list : BeanList = listOf() typealias BeanValidator = (BeanDefinition) -> Boolean typealias BeanList = List<BeanDefinition> val list : BeanList = listOf() typealias BeanValidator = (BeanDefinition) -> Boolean val bv : BeanValidator = { def -> def.name.isNotEmpty()} typealias BeanValidator = (BeanDefinition) -> Boolean val bv : BeanValidator = { def -> def.name.isNotEmpty()} // A Bean definition with post init data class BeanDefinition(val name: String, val clazz: KClass<*>) { fun validate(validator: BeanValidator) : Boolean = validator(this) } // A Bean definition with post init data class BeanDefinition(val name: String, val clazz: KClass<*>) { fun validate(validator: BeanValidator) : Boolean = validator(this) }
40. Type Aliases typealias BeanList = List<BeanDefinition> typealias BeanList = List<BeanDefinition> val list : BeanList = listOf() typealias BeanValidator = (BeanDefinition) -> Boolean typealias BeanList = List<BeanDefinition> val list : BeanList = listOf() typealias BeanValidator = (BeanDefinition) -> Boolean val bv : BeanValidator = { def -> def.name.isNotEmpty()} typealias BeanValidator = (BeanDefinition) -> Boolean val bv : BeanValidator = { def -> def.name.isNotEmpty()} // A Bean definition with post init data class BeanDefinition(val name: String, val clazz: KClass<*>) { fun validate(validator: BeanValidator) : Boolean = validator(this) } // A Bean definition with post init data class BeanDefinition(val name: String, val clazz: KClass<*>) { fun validate(validator: BeanValidator) : Boolean = validator(this) } // A Bean definition with post init data class BeanDefinition(val name: String, val clazz: KClass<*>) { fun validate(validator: BeanValidator) : Boolean = validator(this) }
42. Ready to write our API
43. Making clean syntax StringUtil.capitalize(s) s.capitalize() Extension FuncNon 1.to("one") 1 to "one" Infix call set.add(2) set += 2 Operator overloading map.get("key") map["key"] Get method convenNon StringUtil.capitalize(s) 1.to("one") set.add(2) map.get("key")
44. file.use({f -> f.read()}) file.use {f -> f.read()} Lambda outside parenthesis sb.append("yes") sb.append("no") with (sb){ append("yes") append("no") } Lambda with receiver file.use({f -> f.read()}) sb.append("yes") sb.append("no") Making clean syntax
45. API or DSL?
46. DSL - a small set of features - focus on a particular task declarative API - a set of functions and procedures - for creation of applications imperative => internal DSL
47. Dependency injection DSL
48. provide { MyService() } Builder function Type reference () -> MyService MyService::class fun provide( definition : () -> T )
49. provide { MyServiceA() } declareContext { } provide { MyServiceB( ? ) } provide { MyServiceC( ? , ?) } data class MyServiceA() data class MyServiceB(val a : MyServiceA) data class MyServiceC(val a : MyServiceA, val b : MyServiceB) provide { MyServiceC(get<MyServiceA>(),get<MyServiceB>()) } provide { MyServiceB(get<MyServiceA>()) }
50. fun <T> provide(definition: () -> T) { } data class BeanDefinition(val name: String, val clazz: KClass<*>)
51. fun <T> provide(definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName val bean = BeanDefinition(name,clazz) } data class BeanDefinition(val name: String, val clazz: KClass<*>)
52. inline fun <reified T> provide(definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName val bean = BeanDefinition(definition, name, clazz) } data class BeanDefinition(val name: String, val clazz: KClass<*>)
53. inline fun <reified T> provide(definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName val bean = BeanDefinition(definition, name, clazz) } data class BeanDefinition<T>(val definition: () -> T, val name : String, val clazz : KClass<*>)
54. inline fun <reified T> provide(noinline definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName val bean = BeanDefinition(definition, name, clazz) } data class BeanDefinition<T>(val definition: () -> T, val name : String, val clazz : KClass<*>)
55. class Context { inline fun <reified T> provide(noinline definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName val bean = BeanDefinition(definition, name, clazz) } } data class BeanDefinition<T>(val definition: () -> T, val name : String, val clazz : KClass<*>)
56. class Context { var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> provide(noinline definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName definitions += BeanDefinition(definition, name, clazz) } } data class BeanDefinition<T>(val definition: () -> T, val name : String, val clazz : KClass<*>)
57. class Context { var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> provide(noinline definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName definitions += BeanDefinition(definition, name, clazz) } } data class BeanDefinition<T>(val definition: () -> T, val name : String, val clazz : KClass<*>) fun declareContext(init: Context.() -> Unit) = Context().apply(init)
58. class Context { var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> provide(noinline definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName definitions += BeanDefinition(definition, name, clazz) } } data class BeanDefinition<T>(val definition: () -> T, val name : String, val clazz : KClass<*>) fun declareContext(init: Context.() -> Unit) = Context().apply(init)
59. class Context { var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> provide(noinline definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName definitions += BeanDefinition(definition, name, clazz) } } data class BeanDefinition<T>(val definition: () -> T, val name : String, val clazz : KClass<*>) fun declareContext(init: Context.() -> Unit) = Context().apply(init)
60. declareContext { } provide { MyServiceB( ? ) } provide { MyServiceC( ? , ?) } data class MyServiceA() data class MyServiceB(val a : MyServiceA) data class MyServiceC(val a : MyServiceA, val b : MyServiceB) provide { MyServiceA() } provide { MyServiceC(get<MyServiceA>(),get<MyServiceB>()) } provide { MyServiceB(get<MyServiceA>()) }
61. class Context { var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> provide(noinline definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName definitions += BeanDefinition(definition, name, clazz) } } data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) fun declareContext(init: Context.() -> Unit) = Context().apply(init)
62. data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) fun declareContext(init: Context.() -> Unit) = Context().apply(init) class Context { var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> provide(noinline definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName definitions += BeanDefinition(definition, name, clazz) } } var instances = HashMap<KClass<*>,Any>()
63. data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) fun declareContext(init: Context.() -> Unit) = Context().apply(init) class Context { var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> provide(noinline definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName definitions += BeanDefinition(definition, name, clazz) } fun <T> get() : T{} } var instances = HashMap<KClass<*>,Any>()
64. data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) fun declareContext(init: Context.() -> Unit) = Context().apply(init) class Context { var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> provide(noinline definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName definitions += BeanDefinition(definition, name, clazz) } fun <T> get() : T = instances[T::class] } var instances = HashMap<KClass<*>,Any>()
65. data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) fun declareContext(init: Context.() -> Unit) = Context().apply(init) class Context { var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> provide(noinline definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName definitions += BeanDefinition(definition, name, clazz) } inline fun <reified T> get() : T = instances[T::class] } var instances = HashMap<KClass<*>,Any>()
66. data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) fun declareContext(init: Context.() -> Unit) = Context().apply(init) class Context { var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> provide(noinline definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName definitions += BeanDefinition(definition, name, clazz) } inline fun <reified T> get() : T = instances[T::class] as T } var instances = HashMap<KClass<*>,Any>()
67. provide { MyServiceA() } declareContext { } provide { MyServiceB( ? ) } provide { MyServiceC( ? , ?) } data class MyServiceA() : MyServiceA data class MyServiceB(val a : MyServiceA) data class MyServiceC(val a : MyServiceA, val b : MyServiceB) provide { MyServiceC(get<MyInterface>(),get<MyServiceB>()) } provide { MyServiceB(get<MyServiceA>()) }
68. provide { MyServiceA() } declareContext { } provide { MyServiceB( ? ) } provide { MyServiceC( ? , ?) } data class MyServiceA() : MyServiceA data class MyServiceB(val a : MyServiceA) data class MyServiceC(val a : MyServiceA, val b : MyServiceB) provide { MyServiceC(get<MyInterface>(),get<MyServiceB>()) } provide { MyServiceB(get<MyServiceA>()) } Lazy evaluated by nature!
69. provide { MyServiceA() } declareContext { } data class MyServiceA() : MyServiceA data class MyServiceB(val a : MyServiceA) data class MyServiceC(val a : MyServiceA, val b : MyServiceB) provide { MyServiceC(get(),get()) } provide { MyServiceB(get()) }
70. data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) fun declareContext(init: Context.() -> Unit) = Context().apply(init) class Context { var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> provide(noinline definition: () -> T) { val clazz = T::class val name = clazz.java.simpleName definitions += BeanDefinition(definition, name, clazz) } inline fun <reified T> get() : T = instances[T::class] as T } var instances = HashMap<KClass<*>,Any>()
71. data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) fun declareContext(init: Context.() -> Unit) = Context().apply(init) class Context {...} var instances = HashMap<KClass<*>,Any>()
72. data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) abstract class Module { abstract fun context() : Context } class Context {...} var instances = HashMap<KClass<*>,Any>()
73. data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) abstract class Module { abstract fun context() : Context fun declareContext(init: Context.() -> Unit) = Context().apply(init) } class Context {...} var instances = HashMap<KClass<*>,Any>()
74. class SimpleModule : Module() { override fun context() = declareContext { provide { ServiceA() } provide { ServiceB(get()) } provide { ServiceC(get(), get()) } } } data class MyServiceA() data class MyServiceB(val a : MyServiceA) data class MyServiceC(val a : MyServiceA, val b : MyServiceB) Entirely declarative
75. Dependency resolution API
76. data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) abstract class Module { abstract fun context() : Context fun declareContext(init: Context.() -> Unit) = Context().apply(init) } class Context {...} var instances = HashMap<KClass<*>,Any>()
77. data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) class Context {...} abstract class Module { abstract fun context() : Context fun declareContext(init: Context.() -> Unit) = Context().apply(init) } class CoreContext{ var instances = HashMap<KClass<*>,Any>() var definitions = listOf<BeanDefinition<*>>() }
78. data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) class Context {...} abstract class Module(){ lateinit var coreContext: CoreContext abstract fun context() : Context fun declareContext(init: Context.() -> Unit) = Context(coreContext).apply(init) } class CoreContext{ var instances = HashMap<KClass<*>,Any>() var definitions = listOf<BeanDefinition<*>>() }
79. data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) class Context {...} abstract class Module(){ lateinit var coreContext: CoreContext abstract fun context() : Context fun declareContext(init: Context.() -> Unit) = Context(coreContext).apply(init) } class CoreContext{ var instances = HashMap<KClass<*>,Any>() var definitions = listOf<BeanDefinition<*>>() }
80. data class BeanDefinition<T>(val definition: () -> T, val name: String, val clazz: KClass<*>) class Context(val coreContext: CoreContext) { ... } abstract class Module(){ lateinit var coreContext: CoreContext abstract fun context() : Context fun declareContext(init: Context.() -> Unit) = Context(coreContext).apply(init) } class CoreContext{ var instances = HashMap<KClass<*>,Any>() var definitions = listOf<BeanDefinition<*>>() }
81. class Context(val coreContext: CoreContext) { //... inline fun <reified T> get() : T = instances[T::class] }
82. class Context(val coreContext: CoreContext) { //... inline fun <reified T> get() : T = coreContext.inject() }
83. class CoreContext { var instances = HashMap<KClass<*>, Any>() var definitions = listOf<BeanDefinition<*>>() fun <T> inject(): T {} }
84. class CoreContext { var instances = HashMap<KClass<*>, Any>() var definitions = listOf<BeanDefinition<*>>() fun <T> inject(): T { val clazz = T::class } }
85. class CoreContext { var instances = HashMap<KClass<*>, Any>() var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> inject(): T { val clazz = T::class } }
86. class CoreContext { var instances = HashMap<KClass<*>, Any>() var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> inject(): T { val clazz = T::class // found one ? val foundInstance: T? = instances[clazz] as? T } }
87. class CoreContext { var instances = HashMap<KClass<*>, Any>() var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> inject(): T { val clazz = T::class // found one ? val foundInstance: T? = instances[clazz] as? T // create one ? val createdInstance: T? = if (foundInstance == null) { definitions.firstOrNull { it.clazz == clazz }?.let { it.definition.invoke() as? T? } } else null } }
88. class CoreContext { var instances = HashMap<KClass<*>, Any>() var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> inject(): T { val clazz = T::class // found one ? val foundInstance: T? = instances[clazz] as? T // create one ? val createdInstance: T? = if (foundInstance == null) { definitions.firstOrNull { it.clazz == clazz }?.let { it.definition.invoke() as? T? } } else null } }
89. class CoreContext { var instances = HashMap<KClass<*>, Any>() var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> inject(): T { val clazz = T::class // found one ? val foundInstance: T? = instances[clazz] as? T // create one ? val createdInstance: T? = if (foundInstance == null) { definitions.firstOrNull { it.clazz == clazz }?.let { it.definition.invoke() as? T? } } else null } }
90. class CoreContext { var instances = HashMap<KClass<*>, Any>() var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> inject(): T { val clazz = T::class // found one ? val foundInstance: T? = instances[clazz] as? T // create one ? val createdInstance: T? = if (foundInstance == null) { definitions.firstOrNull { it.clazz == clazz }?.let { it.definition.invoke() as? T? } } else null } }
91. class CoreContext { var instances = HashMap<KClass<*>, Any>() var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> inject(): T { val clazz = T::class // found one ? val foundInstance: T? = instances[clazz] as? T // create one ? val createdInstance: T? = if (foundInstance == null) { definitions.firstOrNull { it.clazz == clazz }?.let { it.definition.invoke() as? T? } } else null // Got it val instance: T = (foundInstance ?: createdInstance) ?: error("Bean $clazz not found") } }
92. class CoreContext { var instances = HashMap<KClass<*>, Any>() var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> inject(): T { val clazz = T::class // found one ? val foundInstance: T? = instances[clazz] as? T // create one ? val createdInstance: T? = if (foundInstance == null) { definitions.firstOrNull { it.clazz == clazz }?.let { it.definition.invoke() as? T? } } else null // Got it val instance: T = (foundInstance ?: createdInstance) ?: error("Bean $clazz not found ») // Save it if (createdInstance != null && foundInstance == null) { instances[clazz] = createdInstance as Any } } }
93. class CoreContext { var instances = HashMap<KClass<*>, Any>() var definitions = listOf<BeanDefinition<*>>() inline fun <reified T> inject(): T { val clazz = T::class // found one ? val foundInstance: T? = instances[clazz] as? T // create one ? val createdInstance: T? = if (foundInstance == null) { definitions.firstOrNull { it.clazz == clazz }?.let { it.definition.invoke() as? T? } } else null // Got it val instance: T = (foundInstance ?: createdInstance) ?: error("Bean $clazz not found") // Save it if (createdInstance != null && foundInstance == null) { instances[clazz] = createdInstance as Any } return instance } }
94. class CoreContext { var instances = HashMap<KClass<*>, Any>() var definitions = listOf<BeanDefinition<*>>() fun <T : Module> build(module: T) {} inline fun <reified T> inject(): T {} }
95. class CoreContext { var instances = HashMap<KClass<*>, Any>() var definitions = listOf<BeanDefinition<*>>() fun <T : Module> build(module: T) { module.coreContext = this } inline fun <reified T> inject(): T {} }
96. class CoreContext { var instances = HashMap<KClass<*>, Any>() var definitions = listOf<BeanDefinition<*>>() fun <T : Module> build(module: T) { module.coreContext = this definitions += module.context().definitions } inline fun <reified T> inject(): T {} }
97. data class MyServiceA() data class MyServiceB(val a : MyServiceA) data class MyServiceC(val a : MyServiceA, val b : MyServiceB) class SimpleModule : Module() { override fun context() = declareContext { provide { ServiceA() } provide { ServiceB(get()) } provide { ServiceC(get(), get()) } } } Let’s use it
98. val ctx = CoreContext() ctx.build(SimpleModule()) data class MyServiceA() data class MyServiceB(val a : MyServiceA) data class MyServiceC(val a : MyServiceA, val b : MyServiceB) class SimpleModule : Module() { override fun context() = declareContext { provide { ServiceA() } provide { ServiceB(get()) } provide { ServiceC(get(), get()) } } }
99. val ctx = CoreContext() ctx.build(SimpleModule()) val serviceB = ctx.inject<MyServiceB>() data class MyServiceA() data class MyServiceB(val a : MyServiceA) data class MyServiceC(val a : MyServiceA, val b : MyServiceB) class SimpleModule : Module() { override fun context() = declareContext { provide { ServiceA() } provide { ServiceB(get()) } provide { ServiceC(get(), get()) } } }
100. No code generation No annotation No introspection No proxy
101. Reflection -> Kclass, KProperty, KFunction … -> Java => Extra lib And also … Extra Binding Lazy Inject
103. https:/ /github.com/Ekito/koin
104. Collections & Concurrency
105. Collections
106. KEEP immutable collections - « real » immutable collections - avoid java backed collections New in 1.1 - Array-Like instantiation - onEach() - minOf/maxOf - groupingBy() - Map : minus(), getValue() Collections
107. Stream API (Kotlin on Java 8+) - toStream() Collection to Sequences (Pure Kotlin or Java 6/7) - asSequence() Lazy Collections
108. sequence.map {…} .filter {…} .toList() Intermediate operations terminal operation sequence.map {…} .filter {…} .toList() sequence.map {…} .filter {…} .toList()
109. Async Programming
110. ⚠ Experimental feature ⚠
111. kotlinx.coroutines
112. Kotlin >= 1.1.4 Gradle: compile ‘org.jetbrains.kotlinx:kotlinx-coroutines-core:0.18’ Remove warnings: kotlin { experimental { coroutines "enable" } }
113. Suspend - keyword, mark function as « suspending function » Coroutines - API for computations that can be suspended without blocking a thread - launched with coroutine builder (light-weight threads)
114. WELCOME TO THE ASYNC WORLD
115. @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } }
116. @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } }
117. @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } }
118. @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } }
119. @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } }
120. @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } @Test fun test() = runBlocking { val main = measureTimeMillis { val jobs = List(100_000) { launch(CommonPool) { delay(1000L) print(".") } } jobs.forEach { it.join() } } println("\ndone in $main") }
121. @Test fun test() = runBlocking { val main = measureTimeMillis { val jobs = List(100_000) { launch(CommonPool) { doSomething() } } jobs.forEach { it.join() } } println("\ndone in $main") } suspend fun doSomething() { delay(1000L) print(".") }
122. suspend fun delay(time: Long, unit: TimeUnit = TimeUnit.MILLISECONDS) {…} suspend fun delay(time: Long, unit: TimeUnit = TimeUnit.MILLISECONDS) public fun <T> runBlocking(context: CoroutineContext = EmptyCoroutineContext, block: suspend CoroutineScope.() -> T): T {…}
123. Kotlin coroutines ~ 1s Java ForkJoin ~ 15s
124. Dispatching jobs
125. @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 }
126. @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 }
127. @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 }
128. @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 }
129. @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 }
130. @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 }
131. @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 }
132. @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 }
133. @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 } @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 }
134. @Test
 fun testWeather() = runBlocking {
 log("starting ...")
 val ws = retrofitWS("https://weather-api.herokuapp.com/")
 try {
 val location = asyncGeocode(ws).await() ?: error("No location :(")
 val weather = asyncWeather(location, ws).await()
 log("got weather : $weather")
 } catch (e: Exception) {
 System.err.println("Error is $e")
 }
 log("finished !")
 }
 
 private fun asyncWeather(location: Location, ws: BlockingWeatherWS): Deferred<Weather> = async(CommonPool) {
 log("get weather for $location")
 ws.weather(location.lat, location.lng, "EN").execute().body()
 }
 
 private fun asyncGeocode(ws: BlockingWeatherWS): Deferred<Location?> = async(CommonPool) {
 log("get location")
 ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 }
135. Data streaming with channels
136. @Test
 fun testWeather() = runBlocking {
 val ws = retrofitWS("https://my-weather-api.herokuapp.com/")
 val time = measureTimeMillis {
 val location = channelLocation(ws)
 val weather = channelWeather(location, ws)
 weather.consumeEach { w ->
 log("got weather : $w")
 }
 location.cancel()
 weather.cancel()
 }
 log("\ndone in $time")
 }
 
 private fun channelWeather(locationChannel: ProducerJob<Location>, ws: BlockingWeatherWS) = produce<Forecastday_>(CommonPool) {
 log("get weather for $locationChannel")
 locationChannel.consumeEach { location ->
 val list = ws.weather(location.lat, location.lng, "EN").execute().body().forecast?.simpleforecast?.forecastday?.take(4).orEmpty()
 list.forEach { send(it) }
 }
 }
 
 private fun channelLocation(ws: BlockingWeatherWS) = produce<Location>(CommonPool) {
 log("get location")
 val location = ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 location?.let {
 send(location)
 }
 }
137. @Test
 fun testWeather() = runBlocking {
 val ws = retrofitWS("https://my-weather-api.herokuapp.com/")
 val time = measureTimeMillis {
 val location = channelLocation(ws)
 val weather = channelWeather(location, ws)
 weather.consumeEach { w ->
 log("got weather : $w")
 }
 location.cancel()
 weather.cancel()
 }
 log("\ndone in $time")
 }
 
 private fun channelWeather(locationChannel: ProducerJob<Location>, ws: BlockingWeatherWS) = produce<Forecastday_>(CommonPool) {
 log("get weather for $locationChannel")
 locationChannel.consumeEach { location ->
 val list = ws.weather(location.lat, location.lng, "EN").execute().body().forecast?.simpleforecast?.forecastday?.take(4).orEmpty()
 list.forEach { send(it) }
 }
 }
 
 private fun channelLocation(ws: BlockingWeatherWS) = produce<Location>(CommonPool) {
 log("get location")
 val location = ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 location?.let {
 send(location)
 }
 }
138. @Test
 fun testWeather() = runBlocking {
 val ws = retrofitWS("https://my-weather-api.herokuapp.com/")
 val time = measureTimeMillis {
 val location = channelLocation(ws)
 val weather = channelWeather(location, ws)
 weather.consumeEach { w ->
 log("got weather : $w")
 }
 location.cancel()
 weather.cancel()
 }
 log("\ndone in $time")
 }
 
 private fun channelWeather(locationChannel: ProducerJob<Location>, ws: BlockingWeatherWS) = produce<Forecastday_>(CommonPool) {
 log("get weather for $locationChannel")
 locationChannel.consumeEach { location ->
 val list = ws.weather(location.lat, location.lng, "EN").execute().body().forecast?.simpleforecast?.forecastday?.take(4).orEmpty()
 list.forEach { send(it) }
 }
 }
 
 private fun channelLocation(ws: BlockingWeatherWS) = produce<Location>(CommonPool) {
 log("get location")
 val location = ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 location?.let {
 send(location)
 }
 }
139. @Test
 fun testWeather() = runBlocking {
 val ws = retrofitWS("https://my-weather-api.herokuapp.com/")
 val time = measureTimeMillis {
 val location = channelLocation(ws)
 val weather = channelWeather(location, ws)
 weather.consumeEach { w ->
 log("got weather : $w")
 }
 location.cancel()
 weather.cancel()
 }
 log("\ndone in $time")
 }
 
 private fun channelWeather(locationChannel: ProducerJob<Location>, ws: BlockingWeatherWS) = produce<Forecastday_>(CommonPool) {
 log("get weather for $locationChannel")
 locationChannel.consumeEach { location ->
 val list = ws.weather(location.lat, location.lng, "EN").execute().body().forecast?.simpleforecast?.forecastday?.take(4).orEmpty()
 list.forEach { send(it) }
 }
 }
 
 private fun channelLocation(ws: BlockingWeatherWS) = produce<Location>(CommonPool) {
 log("get location")
 val location = ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 location?.let {
 send(location)
 }
 }
140. @Test
 fun testWeather() = runBlocking {
 val ws = retrofitWS("https://my-weather-api.herokuapp.com/")
 val time = measureTimeMillis {
 val location = channelLocation(ws)
 val weather = channelWeather(location, ws)
 weather.consumeEach { w ->
 log("got weather : $w")
 }
 location.cancel()
 weather.cancel()
 }
 log("\ndone in $time")
 }
 
 private fun channelWeather(locationChannel: ProducerJob<Location>, ws: BlockingWeatherWS) = produce<Forecastday_>(CommonPool) {
 log("get weather for $locationChannel")
 locationChannel.consumeEach { location ->
 val list = ws.weather(location.lat, location.lng, "EN").execute().body().forecast?.simpleforecast?.forecastday?.take(4).orEmpty()
 list.forEach { send(it) }
 }
 }
 
 private fun channelLocation(ws: BlockingWeatherWS) = produce<Location>(CommonPool) {
 log("get location")
 val location = ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 location?.let {
 send(location)
 }
 }
141. @Test
 fun testWeather() = runBlocking {
 val ws = retrofitWS("https://my-weather-api.herokuapp.com/")
 val time = measureTimeMillis {
 val location = channelLocation(ws)
 val weather = channelWeather(location, ws)
 weather.consumeEach { w ->
 log("got weather : $w")
 }
 location.cancel()
 weather.cancel()
 }
 log("\ndone in $time")
 }
 
 private fun channelWeather(locationChannel: ProducerJob<Location>, ws: BlockingWeatherWS) = produce<Forecastday_>(CommonPool) {
 log("get weather for $locationChannel")
 locationChannel.consumeEach { location ->
 val list = ws.weather(location.lat, location.lng, "EN").execute().body().forecast?.simpleforecast?.forecastday?.take(4).orEmpty()
 list.forEach { send(it) }
 }
 }
 
 private fun channelLocation(ws: BlockingWeatherWS) = produce<Location>(CommonPool) {
 log("get location")
 val location = ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 location?.let {
 send(location)
 }
 }
142. @Test
 fun testWeather() = runBlocking {
 val ws = retrofitWS("https://my-weather-api.herokuapp.com/")
 val time = measureTimeMillis {
 val location = channelLocation(ws)
 val weather = channelWeather(location, ws)
 weather.consumeEach { w ->
 log("got weather : $w")
 }
 location.cancel()
 weather.cancel()
 }
 log("\ndone in $time")
 }
 
 private fun channelWeather(locationChannel: ProducerJob<Location>, ws: BlockingWeatherWS) = produce<Forecastday_>(CommonPool) {
 log("get weather for $locationChannel")
 locationChannel.consumeEach { location ->
 val list = ws.weather(location.lat, location.lng, "EN").execute().body().forecast?.simpleforecast?.forecastday?.take(4).orEmpty()
 list.forEach { send(it) }
 }
 }
 
 private fun channelLocation(ws: BlockingWeatherWS) = produce<Location>(CommonPool) {
 log("get location")
 val location = ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 location?.let {
 send(location)
 }
 }
143. @Test
 fun testWeather() = runBlocking {
 val ws = retrofitWS("https://my-weather-api.herokuapp.com/")
 val time = measureTimeMillis {
 val location = channelLocation(ws)
 val weather = channelWeather(location, ws)
 weather.consumeEach { w ->
 log("got weather : $w")
 }
 location.cancel()
 weather.cancel()
 }
 log("\ndone in $time")
 }
 
 private fun channelWeather(locationChannel: ProducerJob<Location>, ws: BlockingWeatherWS) = produce<Forecastday_>(CommonPool) {
 log("get weather for $locationChannel")
 locationChannel.consumeEach { location ->
 val list = ws.weather(location.lat, location.lng, "EN").execute().body().forecast?.simpleforecast?.forecastday?.take(4).orEmpty()
 list.forEach { send(it) }
 }
 }
 
 private fun channelLocation(ws: BlockingWeatherWS) = produce<Location>(CommonPool) {
 log("get location")
 val location = ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 location?.let {
 send(location)
 }
 }
144. @Test
 fun testWeather() = runBlocking {
 val ws = retrofitWS("https://my-weather-api.herokuapp.com/")
 val time = measureTimeMillis {
 val location = channelLocation(ws)
 val weather = channelWeather(location, ws)
 weather.consumeEach { w ->
 log("got weather : $w")
 }
 location.cancel()
 weather.cancel()
 }
 log("\ndone in $time")
 }
 
 private fun channelWeather(locationChannel: ProducerJob<Location>, ws: BlockingWeatherWS) = produce<Forecastday_>(CommonPool) {
 log("get weather for $locationChannel")
 locationChannel.consumeEach { location ->
 val list = ws.weather(location.lat, location.lng, "EN").execute().body().forecast?.simpleforecast?.forecastday?.take(4).orEmpty()
 list.forEach { send(it) }
 }
 }
 
 private fun channelLocation(ws: BlockingWeatherWS) = produce<Location>(CommonPool) {
 log("get location")
 val location = ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 location?.let {
 send(location)
 }
 }
145. @Test
 fun testWeather() = runBlocking {
 val ws = retrofitWS("https://my-weather-api.herokuapp.com/")
 val time = measureTimeMillis {
 val location = channelLocation(ws)
 val weather = channelWeather(location, ws)
 weather.consumeEach { w ->
 log("got weather : $w")
 }
 location.cancel()
 weather.cancel()
 }
 log("\ndone in $time")
 }
 
 private fun channelWeather(locationChannel: ProducerJob<Location>, ws: BlockingWeatherWS) = produce<Forecastday_>(CommonPool) {
 log("get weather for $locationChannel")
 locationChannel.consumeEach { location ->
 val list = ws.weather(location.lat, location.lng, "EN").execute().body().forecast?.simpleforecast?.forecastday?.take(4).orEmpty()
 list.forEach { send(it) }
 }
 }
 
 private fun channelLocation(ws: BlockingWeatherWS) = produce<Location>(CommonPool) {
 log("get location")
 val location = ws.geocode("Toulouse,fr").execute().body().results.first().geometry?.location
 location?.let {
 send(location)
 }
 }
146. Coroutines - builder (runBlocking, async, launch …) - primitives (delay, measureTime, job…) - communication (deferred, channel, selector, actor …) => Reactive world (RxJava …) => UI (JavaFX, Android …) => Testing (?)
147. Further reading https:/ /github.com/Kotlin/kotlinx.coroutines/blob/master/coroutines-guide.md https:/ /github.com/Kotlin/kotlinx.coroutines/blob/master/ui/coroutines-guide-ui.md https:/ /github.com/Kotlin/anko/wiki/Anko-Coroutines https:/ /akarnokd.blogspot.fr/2017/09/rxjava-vs-kotlin-coroutines-quick-look.html?m=1 https:/ /github.com/Kotlin/kotlinx.coroutines/blob/master/reactive/coroutines- guide-reactive.md Coroutines vs RxJava
148. Beyond Kotlin Playground https:/ /github.com/Ekito/beyond-kotlin-playground
149. What’s next?
150. On the road to Kotlin 1.2 https:/ /blog.jetbrains.com/kotlin/2017/08/kotlin-1-2-m2-is-out/ https:/ /blog.jetbrains.com/kotlin/2017/06/early-access-program-for- kotlin-1-2-has-been-started/
151. Others stuffs in 1.1 https:/ /kotlinlang.org/docs/reference/whatsnew11.html Gradle Kotlin Scripts https:/ /github.com/gradle/kotlin-dsl Kotlin Native https:/ /github.com/JetBrains/kotlin-native
152. Thank you :)