Multiplatform Functional Architecture with Oolong

Software development is becoming increasingly functional, and for good reason. Functional programming principles like abstraction and composition enable safe, scalable, feature-driven applications. Learn how Oolong uses the Model-View-Update architectural pattern to help you write software with confidence and ease.

Transcript

2. Multiplatform Functional Architecture
3. Multiplatform Functional Architecture with Oolong
5. Different codebases solving the same problems.
9. Multiplatform Functional Architecture
10. https://kotlinlang.org/docs/reference/multiplatform.html
11. Multiplatform Functional Architecture
12. λx.x a └┬─┘ Application Body ┌┴┐ Variable ┌┴┐ └───┬────┘ Abstraction
13. (λU.(λY.(λvoid.(λ0.(λsucc.(λ+.(λ*.(λ1.(λ2.(λ3.(λ4.(λ5.(λ6.(λ7.(λ8.(λ9.(λ10.(λnum.(λtrue.(λfalse.(λif.(λnot. (λand.(λor.(λmake-pair.(λpair-first.(λpair-second.(λzero?.(λpred.(λ-.(λeq?.(λ/.(λ%.(λnil.(λnil?.(λcons. (λcar.(λcdr.(λdo2.(λdo3.(λdo4.(λfor.(λprint-byte.(λprint-list.(λprint-newline.(λzero-byte.(λitoa.(λfizzmsg. (λbuzzmsg.(λfizzbuzzmsg.(λfizzbuzz.(fizzbuzz (((num 1) 0) 1)) λn.((for n) λi.((do2 (((if (zero? ((% i) 3))) λ_.(((if (zero? ((% i) 5))) λ_.(print-list fizzbuzzmsg)) λ_.(print-list fizzmsg))) λ_.(((if (zero? ((% i) 5))) λ_.(print-list buzzmsg)) λ_.(print-list (itoa i))))) (print-newline nil)))) ((cons (((num 0) 7) 0)) ((cons (((num 1) 0) 5)) ((cons (((num 1) 2) 2)) ((cons (((num 1) 2) 2)) ((cons (((num 0) 9) 8)) ((cons (((num 1) 1) 7)) ((cons (((num 1) 2) 2)) ((cons (((num 1) 2) 2)) nil))))))))) ((cons (((num 0) 6) 6)) ((cons (((num 1) 1) 7)) ((cons (((num 1) 2) 2)) ((cons (((num 1) 2) 2)) nil))))) ((cons (((num 0) 7) 0)) ((cons (((num 1) 0) 5)) ((cons (((num 1) 2) 2)) ((cons (((num 1) 2) 2)) nil))))) λn.(((Y λrecurse.λn.λresult.(((if (zero? n)) λ_.(((if (nil? result)) λ_.((cons zero-byte) nil)) λ_.result)) λ_. ((recurse ((/ n) 10)) ((cons ((+ zero-byte) ((% n) 10))) result)))) n) nil)) (((num 0) 4) 8)) λ_.(print- byte (((num 0) 1) 0))) (Y λrecurse.λl.(((if (nil? l)) λ_.void) λ_.((do2 (print-byte (car l))) (recurse (cdr l)))))) PRINT_BYTE) λn.λf.((((Y λrecurse.λremaining.λcurrent.λf.(((if (zero? remaining)) λ_.void) λ_.((do2 (f current)) (((recurse (pred remaining)) (succ current)) f)))) n) 0) f)) λa.do3) λa.do2) λa.λb.b) λl. (pair-second (pair-second l))) λl.(pair-first (pair-second l))) λe.λl.((make-pair true) ((make-pair e) l))) λl.(not (pair-first l))) ((make-pair false) void)) λm.λn.((- m) ((* ((/ m) n)) n))) (Y λ/.λm.λn.(((if ((eq? m) n)) λ_.1) λ_.(((if (zero? ((- m) n))) λ_.0) λ_.((+ 1) ((/ ((- m) n)) n)))))) λm.λn.((and (zero? ((- m) n))) (zero? ((- n) m)))) λm.λn.((n pred) m)) λn.(((λn.λf.λx.(pair-second ((n λp.((make-pair (f (pair-first p))) (pair-first p))) ((make-pair x) x))) n) succ) 0)) λn.((n λ_.false) true)) λp.(p false)) λp.(p true)) λx.λy.λt.((t x) y)) λa.λb.((a true) b)) λa.λb.((a b) false)) λp.λt.λf.((p f) t)) λp.λa.λb.(((p a) b) void)) λt.λf.f) λt.λf.t) λa.λb.λc.((+ ((+ ((* ((* 10) 10)) a)) ((* 10) b))) c)) (succ 9)) (succ 8)) (succ 7)) (succ 6)) (succ 5)) (succ 4)) (succ 3)) (succ 2)) (succ 1)) (succ 0)) λm.λn.λx.(m (n x))) λm.λn.λf.λx.((((m succ) n) f) x)) λn.λf.λx.(f ((n f) x))) λf.λx.x) λx.(U U)) (U λh.λf.(f λx.(((h h) f) x)))) λf.(f f))
14. Pure functions
15. Pure functions are deterministic.
16. Pure functions are free of side-effects.
17. Functional programming is abstraction and composition.
18. Multiplatform Functional Architecture
19. Boundaries
20. Impure Pure
24. Functional architecture is abstraction and composition.
25. Purity
26. Purity Boundaries
27. Purity Boundaries Composition
28. Architecture Patterns are architecture style + context.
29. Model View Update UI architecture pattern
30. Oolong MVU for Kotlin Multiplatform https://oolong-kt.org
45. https://staltz.com/unidirectional-user-interface-architectures.html#elm
46. Purity
50. data class Model( )
51. data class Model( val count: Int )
52. data class Model( val count: Int ) sealed class Msg { }
53. data class Model( val count: Int ) sealed class Msg { object Increment : Msg() }
54. data class Model( val count: Int ) sealed class Msg { object Increment : Msg() object Decrement : Msg() }
55. data class Model( val count: Int ) sealed class Msg { object Increment : Msg() object Decrement : Msg() } data class Props( )
56. data class Model( val count: Int ) sealed class Msg { object Increment : Msg() object Decrement : Msg() } data class Props( val count: Int, )
57. data class Model( val count: Int ) sealed class Msg { object Increment : Msg() object Decrement : Msg() } data class Props( val count: Int, val increment: (Dispatch<Msg>) -> Unit, )
58. data class Model( val count: Int ) sealed class Msg { object Increment : Msg() object Decrement : Msg() } data class Props( val count: Int, val increment: (Dispatch<Msg>) -> Unit, val decrement: (Dispatch<Msg>) -> Unit, )
59. typealias Dispatch<Msg>
60. typealias Dispatch<Msg> = (Msg) -> Unit
63. val init: () -> Pair<Model, Effect<Msg>> = { }
64. val init: () -> Pair<Model, Effect<Msg>> = { Model(count = 0) }
65. val init: () -> Pair<Model, Effect<Msg>> = { Model(count = 0) to none() }
66. val update: (Msg, Model) -> Pair<Model, Effect<Msg>> = { msg, model -> }
67. val update: (Msg, Model) -> Pair<Model, Effect<Msg>> = { msg, model -> when (msg) { } }
68. val update: (Msg, Model) -> Pair<Model, Effect<Msg>> = { msg, model -> when (msg) { Increment -> } }
69. val update: (Msg, Model) -> Pair<Model, Effect<Msg>> = { msg, model -> when (msg) { Increment -> model.copy(count = model.count + 1) } }
70. val update: (Msg, Model) -> Pair<Model, Effect<Msg>> = { msg, model -> when (msg) { Increment -> model.copy(count = model.count + 1) Decrement -> } }
71. val update: (Msg, Model) -> Pair<Model, Effect<Msg>> = { msg, model -> when (msg) { Increment -> model.copy(count = model.count + 1) Decrement -> model.copy(count = model.count - 1) } }
72. val update: (Msg, Model) -> Pair<Model, Effect<Msg>> = { msg, model -> when (msg) { Increment -> model.copy(count = model.count + 1) Decrement -> model.copy(count = model.count - 1) } to none() }
73. val view: (Model) -> Props = { model -> }
74. val view: (Model) -> Props = { model -> Props( ) }
75. val view: (Model) -> Props = { model -> Props( count = model.count, ) }
76. val view: (Model) -> Props = { model -> Props( count = model.count, increment = { dispatch -> dispatch(Increment) }, ) }
77. val view: (Model) -> Props = { model -> Props( count = model.count, increment = { dispatch -> dispatch(Increment) }, decrement = { dispatch -> dispatch(Decrement) }, ) }
78. runtime( init, update, view, render )
79. runtime( init, update, view, render )
80. runtime( init, update, view, render )
81. val render: (Props, Dispatch<Msg>) -> Any? = { props, dispatch -> }
82. val render: (Props, Dispatch<Msg>) -> Any? = { props, dispatch -> setContent { } }
83. val render: (Props, Dispatch<Msg>) -> Any? = { props, dispatch -> setContent { Counter(props, dispatch) } }
84. @Composable fun Counter(props: Props, dispatch: Dispatch<Msg>) { }
85. @Composable fun Counter(props: Props, dispatch: Dispatch<Msg>) { OutlinedButton(onClick = { }) { Icon(vectorResource(R.drawable.ic_decrement)) } }
86. @Composable fun Counter(props: Props, dispatch: Dispatch<Msg>) { OutlinedButton(onClick = { props.decrement(dispatch) }) { Icon(vectorResource(R.drawable.ic_decrement)) } }
87. @Composable fun Counter(props: Props, dispatch: Dispatch<Msg>) { OutlinedButton(onClick = { props.decrement(dispatch) }) { Icon(vectorResource(R.drawable.ic_decrement)) } Text("") }
88. @Composable fun Counter(props: Props, dispatch: Dispatch<Msg>) { OutlinedButton(onClick = { props.decrement(dispatch) }) { Icon(vectorResource(R.drawable.ic_decrement)) } Text("${props.count}") }
89. @Composable fun Counter(props: Props, dispatch: Dispatch<Msg>) { OutlinedButton(onClick = { props.decrement(dispatch) }) { Icon(vectorResource(R.drawable.ic_decrement)) } Text("${props.count}") Button(onClick = { }) { Icon(vectorResource(R.drawable.ic_increment)) } }
90. @Composable fun Counter(props: Props, dispatch: Dispatch<Msg>) { OutlinedButton(onClick = { props.decrement(dispatch) }) { Icon(vectorResource(R.drawable.ic_decrement)) } Text("${props.count}") Button(onClick = { props.increment(dispatch) }) { Icon(vectorResource(R.drawable.ic_increment)) } }
91. Testing
92. @Test fun `initial Model count should be 0`() { }
93. @Test fun `initial Model count should be 0`() { val expected = Model(count = 0) }
94. @Test fun `initial Model count should be 0`() { val expected = Model(count = 0) val (actual, _) = init() }
95. @Test fun `initial Model count should be 0`() { val expected = Model(count = 0) val (actual, _) = init() assertEquals(expected, actual) }
96. @Test fun `Increment msg should increment Model count`() { }
97. @Test fun `Increment msg should increment Model count`() { val msg = Msg.Increment val model = Model(count = 0) val expected = Model(count = 1) }
98. @Test fun `Increment msg should increment Model count`() { val msg = Msg.Increment val model = Model(count = 0) val expected = Model(count = 1) val (actual, _) = update(msg, model) }
99. @Test fun `Increment msg should increment Model count`() { val msg = Msg.Increment val model = Model(count = 0) val expected = Model(count = 1) val (actual, _) = update(msg, model) assertEquals(expected, actual) }
100. @Test fun `Decrement msg should increment Model count`() { }
101. @Test fun `Decrement msg should increment Model count`() { val msg = Msg.Decrement val model = Model(count = 0) val expected = Model(count = -1) }
102. @Test fun `Decrement msg should increment Model count`() { val msg = Msg.Decrement val model = Model(count = 0) val expected = Model(count = -1) val (actual, _) = update(msg, model) }
103. @Test fun `Decrement msg should increment Model count`() { val msg = Msg.Decrement val model = Model(count = 0) val expected = Model(count = -1) val (actual, _) = update(msg, model) assertEquals(expected, actual) }
104. @Test fun `Props count should be equal to Model count`() { }
105. @Test fun `Props count should be equal to Model count`() { val model = Model(count = 0) val expected = model.count }
106. @Test fun `Props count should be equal to Model count`() { val model = Model(count = 0) val expected = model.count val props = view(model) val actual = props.count }
107. @Test fun `Props count should be equal to Model count`() { val model = Model(count = 0) val expected = model.count val props = view(model) val actual = props.count assertEquals(expected, actual) }
108. @Test fun `Props increment should dispatch Increment msg`() { }
109. @Test fun `Props increment should dispatch Increment msg`() { val model = Model(count = 0) val props = view(model) }
110. @Test fun `Props increment should dispatch Increment msg`() { val model = Model(count = 0) val props = view(model) props.increment { msg -> } }
111. @Test fun `Props increment should dispatch Increment msg`() { val model = Model(count = 0) val props = view(model) props.increment { msg -> assertEquals(msg, Msg.Increment) } }
112. @Test fun `Props decrement should dispatch Decrement msg`() { }
113. @Test fun `Props decrement should dispatch Decrement msg`() { val model = Model(count = 0) val props = view(model) }
114. @Test fun `Props decrement should dispatch Decrement msg`() { val model = Model(count = 0) val props = view(model) props.decrement { msg -> } }
115. @Test fun `Props decrement should dispatch Decrement msg`() { val model = Model(count = 0) val props = view(model) props.decrement { msg -> assertEquals(msg, Msg.Decrement) } }
116. Boundaries
117. typealias GetCount
118. typealias GetCount = () -> Int
119. typealias GetCount = () -> Int typealias PutCount
120. typealias GetCount = () -> Int typealias PutCount = (Int) -> Unit
121. class CounterService(context: Context) { }
122. class CounterService(context: Context) { private val prefs = context.getSharedPreferences("counter", MODE_PRIVATE) }
123. class CounterService(context: Context) { private val prefs = context.getSharedPreferences("counter", MODE_PRIVATE) val getCount: GetCount = { } }
124. class CounterService(context: Context) { private val prefs = context.getSharedPreferences("counter", MODE_PRIVATE) val getCount: GetCount = { prefs.getInt("count", 0) } }
125. class CounterService(context: Context) { private val prefs = context.getSharedPreferences("counter", MODE_PRIVATE) val getCount: GetCount = { prefs.getInt("count", 0) } val putCount: PutCount = { count -> } }
126. class CounterService(context: Context) { private val prefs = context.getSharedPreferences("counter", MODE_PRIVATE) val getCount: GetCount = { prefs.getInt("count", 0) } val putCount: PutCount = { count -> prefs.edit().putInt("count", count).apply() } }
127. { } { count -> } // typealias GetCount = () -> Int // typealias PutCount = (Int) -> Unit val getCount: GetCount = val putCount: PutCount =
128. Side Effects
129. Managed Effects
133. typealias Effect<Msg>
134. typealias Effect<Msg> = (Dispatch<Msg>) -> Any?
135. typealias Effect<Msg> = suspend (Dispatch<Msg>) -> Any?
136. typealias Effect<Msg> = suspend CoroutineScope.(Dispatch<Msg>) -> Any?
137. private val getCountEffect: (GetCount) -> Effect<Msg> = { getCount -> }.
138. private val getCountEffect: (GetCount) -> Effect<Msg> = { getCount -> effect { dispatch -> } }.
139. private val getCountEffect: (GetCount) -> Effect<Msg> = { getCount -> effect { dispatch -> val count = getCount() } }.
140. private val getCountEffect: (GetCount) -> Effect<Msg> = { getCount -> effect { dispatch -> val count = getCount() dispatch(Msg.SetCount(count)) } }.
141. private val putCountEffect: (PutCount) -> (Int) -> Effect<Msg> = { putCount -> }.
142. private val putCountEffect: (PutCount) -> (Int) -> Effect<Msg> = {.putCount -> { count -> }, }.
143. private val putCountEffect: (PutCount) -> (Int) -> Effect<Msg> = {.putCount -> { count -> effect { } }, }.
144. private val putCountEffect: (PutCount) -> (Int) -> Effect<Msg> = {.putCount -> { count -> effect { putCount(count) } }, }.
145. val init: () -> Pair<Model, Effect<Msg>> = { Model(count = 0) to none() }
146. val init: (GetCount) -> () -> Pair<Model, Effect<Msg>> = {.getCount -> { Model(count = 0) to none() } }.
147. val init: (GetCount) -> () -> Pair<Model, Effect<Msg>> = {.getCount -> { Model(count = 0) to none() } }
148. val init: (GetCount) -> () -> Pair<Model, Effect<Msg>> = {.getCount -> { Model(count = 0) to getCountEffect(getCount) } }
149. sealed class Msg { object Increment : Msg() object Decrement : Msg() }
150. sealed class Msg { class SetCount(val count: Int) : Msg() object Increment : Msg() object Decrement : Msg() }
151. val update: (Msg, Model) -> Pair<Model, Effect<Msg>> = { msg, model -> when (msg) { Increment -> model.copy(count = model.count + 1) Decrement -> model.copy(count = model.count - 1) } to none() }
152. val update: (Msg, Model) -> Pair<Model, Effect<Msg>> = { msg, model -> when (msg) { is SetCount -> Increment -> model.copy(count = model.count + 1) Decrement -> model.copy(count = model.count - 1) } to none() }
153. val update: (Msg, Model) -> Pair<Model, Effect<Msg>> = { msg, model -> when (msg) { is SetCount -> model.copy(count = msg.count). Increment -> model.copy(count = model.count + 1). Decrement -> model.copy(count = model.count - 1). } to none() }
154. val update: (PutCount) -> (Msg, Model) -> Pair<Model, Effect<Msg>> = { putCount -> { msg, model -> when (msg) { is SetCount -> model.copy(count = msg.count) Increment -> model.copy(count = model.count + 1) Decrement -> model.copy(count = model.count - 1) } to none() } }
155. val update: (PutCount) -> (Msg, Model) -> Pair<Model, Effect<Msg>> = { putCount -> val putCountEffect = putCountEffect(putCount) { msg, model -> when (msg) { is SetCount -> model.copy(count = msg.count) Increment -> model.copy(count = model.count + 1) Decrement -> model.copy(count = model.count - 1) } to none() } }
156. val update: (PutCount) -> (Msg, Model) -> Pair<Model, Effect<Msg>> = { putCount -> val putCountEffect = putCountEffect(putCount) { msg, model -> when (msg) { is SetCount -> model.copy(count = msg.count) Increment -> model.copy(count = model.count + 1) Decrement -> model.copy(count = model.count - 1) } to none() } }
157. val update: (PutCount) -> (Msg, Model) -> Pair<Model, Effect<Msg>> = { putCount -> val putCountEffect = putCountEffect(putCount) { msg, model -> when (msg) { is SetCount -> model.copy(count = msg.count) Increment -> model.copy(count = model.count + 1) Decrement -> model.copy(count = model.count - 1) } to putCountEffect(model.count) } }
158. runtime( init, update, view, render )
159. runtime( init, update, view, render )
160. runtime( init(counterService.getCount), update, view, render )
161. runtime( init(counterService.getCount), update, view, render )
162. runtime( init(counterService.getCount), update(counterService.putCount), view, render )
163. @Test fun `initial Effect should dispatch SetCount`() { }
164. @Test fun `initial Effect should dispatch SetCount`() { val getCount: GetCount = { 0 } val expected = Msg.SetCount(getCount()) val (_, effect) = init() }
165. @Test fun `initial Effect should dispatch SetCount`() { val getCount: GetCount = { 0 } val expected = Msg.SetCount(getCount()) val (_, effect) = init() runBlocking { effect { actual -> } } }
166. @Test fun `initial Effect should dispatch SetCount`() { val getCount: GetCount = { 0 } val expected = Msg.SetCount(getCount()) val (_, effect) = init() runBlocking { effect { actual -> assertEquals(expected, actual) } } }
167. @Test fun `update effect should put count`() { }
168. @Test fun `update effect should put count`() { val msg = Msg.SetCount(count = 42) val model = Model(count = 0) val putCount: PutCount = { count -> } }
169. @Test fun `update effect should put count`() { val msg = Msg.SetCount(count = 42) val model = Model(count = 0) val putCount: PutCount = { count -> } val (_, effect) = update(putCount)(msg, model) runBlocking { effect { } } }
170. @Test fun `update effect should put count`() { val msg = Msg.SetCount(count = 42) val model = Model(count = 0) val putCount: PutCount = { count -> assertEquals(count, msg.count) } val (_, effect) = update(putCount)(msg, model) runBlocking { effect { } } }
171. Composition
173. object Child { }
174. object Child { class Model }
175. object Child { class Model class Msg }
176. object Child { class Model class Msg class Props }
177. object Child { class Model class Msg class Props val init: () -> Pair<Model, Effect<Msg>> = ... }
178. object Child { class Model class Msg class Props val init: () -> Pair<Model, Effect<Msg>> = ... val update: (Msg, Model) -> Pair<Model, Effect<Msg>> = ... }
179. object Child { class Model class Msg class Props val init: () -> Pair<Model, Effect<Msg>> = ... val update: (Msg, Model) -> Pair<Model, Effect<Msg>> = ... val view: (Model) -> Props = ... }
180. object Child { class Model class Msg class Props val init: () -> Pair<Model, Effect<Msg>> = ... val update: (Msg, Model) -> Pair<Model, Effect<Msg>> = ... val view: (Model) -> Props = ... }
181. object Parent { class.Model class Msg class Props val init: () -> Pair<Model, Effect<Msg>> = ... val update: (Msg, Model).-> Pair<Model, Effect<Msg>> = ... val view: (Model).-> Props = ... }
182. class Model( val child: Child.Model )
183. sealed class Msg { class ChildMsg( val child: Child.Msg ) : Msg() }
184. class Props( val child: Child.Props )
185. val init: () -> Pair<Model, Effect<Msg>> = { // Child.init() }
186. val update: (Msg, Model) -> Pair<Model, Effect<Msg>> = { msg, model -> // Child.update() }
187. val view: (Model) -> Props = { model -> // Child.view() }
188. data class Model( )
189. data class Model( val counters: Map<Id, Counter.Model> )
190. sealed class Msg { }
191. sealed class Msg { class SetCounts(val counts: Map<Id, Int>) : Msg() object AddCounter : Msg() class RemoveCounter(val id: Id) : Msg() class CounterMsg( val id: Id, val msg: Counter.Msg ) : Msg() }
192. class Props( )
193. class Props( val counters: List<CounterRow>, val addCounter: (Dispatch<Msg>) -> Unit, )
194. class Props( val counters: List<CounterRow>, val addCounter: (Dispatch<Msg>) -> Unit, ) { class CounterRow( ) }
195. class Props( val counters: List<CounterRow>, val addCounter: (Dispatch<Msg>) -> Unit, ) { class CounterRow( val props: Counter.Props, val removeCounter: (Dispatch<Msg>) -> Unit, ) }
196. github.com/pardom/mfa-with-oolong
197. What Have We Learned?
198. Purity
199. Purity Boundaries
200. Purity Boundaries Composition
201. Architecture Patterns are architecture style + context.
202. Model View Update UI architecture pattern
204. Multiplatform Functional Architecture with Oolong • oolong-kt.org • guide.elm-lang.org • github.com/pardom/mfa-with-oolong