Functional Programming with Arrow in Kotlin

GIDS 2019: https://www.developermarch.com/developersummit/session.html?insert=Raghunath

With a rising trend in programming languages adding more and more functional capabilities, developers are working at a much higher level of abstraction. The declarative style of programming allows us to write readable and maintainable code that focuses on "what" (larger picture) rather than "how" (nuts and bolts). Functional programming also promotes immutability by default which makes dealing with concurrency an easy and a fun affair. Kotlin already supports some of these features like functions as first-class citizens, lambdas, anonymous functions, immutability, persistent collections, explicit nullable and non-nullable types, declarative constructs, etc., However, these features lack capabilities offered by purely functional languages.

Arrow is a Kotlin library that pushes the envelope further by introducing typeclasses, functional data types, optics, etc., It achieves this by clever usage of Kotlin language features and by generating code using annotation processors.

This talk will walk you through several ideas and code examples that will help you get started with functional programming using Arrow.

Audience will be able to:
- Use functional data types from the Arrow library.
- Use functional programming patterns.
- Solve problems using functional ideas and gradually move away from imperative programming.
- Deal with immutability and use optics to modify deeply nested data structures efficiently.

Transcript

1. Functional Programming with Arrow in Kotlin @ragunathjawahar • Obvious (previously, Uncommon Bangalore)
2. fun findFirst(array: Array<Char>, key: Char): Int { for (i in array.indices) { if (array[i] == key) return i } return -1 }
3. fun findFirst(array: Array<Char>, key: Char): Int { for (i in array.indices) { if (array[i] == key) return i } return -1 }
4. fun findFirst(array: Array<Char>, key: Char): Int { for (i in array.indices) { if (array[i] == key) return i } return -1 }
5. fun findFirst(array: Array<Char>, key: Char): Int { for (i in array.indices) { if (array[i] == key) return i } return -1 }
6. fun findFirst(array: Array<Char>, key: Char): Int { for (i in array.indices) { if (array[i] == key) return i } return -1 }
7. fun findFirst(array: Array<Char>, key: Char): Int { for (i in array.indices) { if (array[i] == key) return i } return -1 }
8. fun findFirst(array: Array<Char>, key: Char): Int { for (i in array.indices) { if (array[i] == key) return i } return -1 }
9. fun findFirst(array: Array<Char>, key: Char): Int { for (i in array.indices) { if (array[i] == key) return i } return -1 }
10. fun findFirst(array: Array<Char>, key: Char): Int { for (i in array.indices) { if (array[i] == key) return i } return -1 }
11. fun findFirst(array: Array<Char>, key: Char): Int { for (i in array.indices) { if (array[i] == key) return i } return -1 }
12. fun findFirst(array: Array<Char>, key: Char): Int { for (i in array.indices) { if (array[i] == key) return i } return -1 }
13. fun findFirst(array: Array<Char>, key: Char): Int { for (i in array.indices) { if (array[i] == key) return i } return -1 }
14. fun findFirst(array: Array<Char>, key: Char): Index { for (i in array.indices) { if (array[i] == key) return i } return -1 } typealias Index = Int
15. fun findFirst(array: Array<Char>, key: Char): Index { for (i in array.indices) { if (array[i] == key) return i } return -1 } typealias Index = Int
16. fun findFirst(array: Array<Char>, key: Char): Index { for (i in array.indices) { if (array[i] == key) return i } return -1 } typealias Index = Int
17. fun findFirst(array: Array<Char>, key: Char): Index { for (i in array.indices) { if (array[i] == key) return i } return -1 } typealias Index = Int // findFirst(chars, ‘e’) != -1
18. fun findFirst(array: Array<Char>, key: Char): Index { for (i in array.indices) { if (array[i] == key) return i } return -1 } typealias Index = Int // findFirst(chars, ‘e’) != -1
19. fun findFirst(array: Array<Char>, key: Char): Index { for (i in array.indices) { if (array[i] == key) return i } return -1 } typealias Index = Int
20. fun findFirst(array: Array<Char>, key: Char): Index? { for (i in array.indices) { if (array[i] == key) return i } return null } typealias Index = Int
21. fun findFirst(array: Array<Char>, key: Char): Option<Index> { for (i in array.indices) { if (array[i] == key) return Some(i) } return None } typealias Index = Int
22. fun findFirst(array: Array<Char>, key: Char): Option<Index> { for (i in array.indices) { if (array[i] == key) return Some(i) } return None } typealias Index = Int // absence // presence
23. fun findFirst(array: Array<Char>, key: Char): Option<Index> { for (i in array.indices) { if (array[i] == key) return Some(i) } return None } typealias Index = Int
24. fun findFirst(array: Array<Char>, key: Char): Option<Index> { for (i in array.indices) { if (array[i] == key) return Some(i) } return None } typealias Index = Int
25. fun findFirst(array: Array<Char>, key: Char): Option<Index> { for (i in array.indices) { if (array[i] == key) return Some(i) } return None } typealias Index = Int
26. fun <A> findFirst(array: Array<A>, key: A): Option<Index> { for (i in array.indices) { if (array[i] == key) return Some(i) } return None } typealias Index = Int
27. fun <A> findFirst(array: Array<A>, key: A): Option<Index> { for (i in array.indices) { if (array[i] == key) return Some(i) } return None } typealias Index = Int
28. fun <A> findFirst(array: Array<A>, key: A): Option<Index> { for (i in array.indices) { if (array[i] == key) return Some(i) } return None } typealias Index = Int
29. fun <A> findFirst(array: Array<A>, p: (A) -> Boolean): Option<Index> { for (i in array.indices) { if (p(array[i])) return Some(i) } return None } typealias Index = Int
30. fun <A> findFirst(array: Array<A>, p: (A) -> Boolean): Option<Index> { for (i in array.indices) { if (p(array[i])) return Some(i) } return None } typealias Index = Int // findFirst(people, { it.firstName == “Ajay” })
31. fun <A> findFirst(array: Array<A>, p: (A) -> Boolean): Option<Index> { for (i in array.indices) { if (p(array[i])) return Some(i) } return None } typealias Index = Int // findFirst(people) { it.firstName == “Ajay” }
32. fun <A> findFirst(array: Array<A>, p: (A) -> Boolean): Option<Index> { for (i in array.indices) { if (p(array[i])) return Some(i) } return None } typealias Index = Int
33. fun <A> findFirst(array: Array<A>, p: (A) -> Boolean): Option<Index> { for (i in array.indices) { if (p(array[i])) return Some(i) } return None } typealias Index = Int
34. fun <A> findFirst(array: Array<A>, p: (A) -> Boolean): Option<Index> { for (i in array.indices) { if (p(array[i])) return Some(i) } return None } typealias Index = Int // findFirst(people) { it.firstName == “Ajay” }
35. fun <A> Array<A>.findFirst(p:,(A) -> Boolean): Option<Index> { for (i in this.indices) { if (p(this[i])) return Some(i) } return None } typealias Index = Int // people.findFirst { it.firstName == “Ajay” }
36. fun <A> Array<A>.findFirst(p:,(A) -> Boolean): Option<Index> { for (i in this.indices) { if (p(this[i])) return Some(i) } return None } typealias Index = Int
37. fun <A> Array<A>.findFirst(p:,(A) -> Boolean): Option<Index> { for (i in this.indices) { if (p(this[i])) return Some(i) } return None } fun findFirst(array: Array<Char>, key: Char): Int { for (i in array.indices) { if (array[i] == key) return i } return -1 }
38. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
39. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
40. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
41. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
42. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
43. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
44. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
45. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
46. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
47. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
48. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
49. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
50. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
51. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
52. fun <A> findFirst(array: Array<A>, p:,(A) -> Boolean): Option<Index> { tailrec fun go(array: Array<A>, index: Index): Option<Index> { return when { index == array.size -> None p(array[index]) -> Some(index) else -> go(array, index + 1) } } return go(array, 0) } But!
53. Core Ideas
54. Core Ideas • Purity • Referential Transparency • Immutability • Lazy Evaluation
55. Notations
56. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
57. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
58. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
59. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
60. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
61. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
62. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
63. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
64. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
65. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
66. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
67. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
68. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b } // (a: Int, b: Int) -> Int
69. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
70. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
71. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
72. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
73. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
74. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
75. fun add(a: Int, b: Int): Int = a + b val addRef: (Int, Int) -> Int = ::add val subtractLambda = { a: Int, b: Int -> a - b }
76. val addRef: (Int, Int) -> Int = ::add addRef.invoke(4, 5) addRef(4, 5)
77. Arrow Syntax compile "io.arrow-kt:arrow-syntax:$arrow_version"
78. val bold: (String) -> String = { "<b>$it</b>" } val italic: (String) -> String = { "<i>$it</i>" } val boldItalic = bold compose italic val italicBold = bold forwardCompose italic Composition
79. val bold: (String) -> String = { "<b>$it</b>" } val italic: (String) -> String = { "<i>$it</i>" } val boldItalic = bold compose italic val italicBold = bold forwardCompose italic Composition
80. val bold: (String) -> String = { "<b>$it</b>" } val italic: (String) -> String = { "<i>$it</i>" } val boldItalic = bold compose italic val italicBold = bold forwardCompose italic Composition // bold(“Hello”)
81. val bold: (String) -> String = { "<b>$it</b>" } val italic: (String) -> String = { "<i>$it</i>" } val boldItalic = bold compose italic val italicBold = bold forwardCompose italic Composition // <b>Hello</b>
82. val bold: (String) -> String = { "<b>$it</b>" } val italic: (String) -> String = { "<i>$it</i>" } val boldItalic = bold compose italic val italicBold = bold forwardCompose italic Composition
83. val bold: (String) -> String = { "<b>$it</b>" } val italic: (String) -> String = { "<i>$it</i>" } val boldItalic = bold compose italic val italicBold = bold forwardCompose italic Composition // italic(“Hello”)
84. val bold: (String) -> String = { "<b>$it</b>" } val italic: (String) -> String = { "<i>$it</i>" } val boldItalic = bold compose italic val italicBold = bold forwardCompose italic Composition // <i>Hello</i>
85. val bold: (String) -> String = { "<b>$it</b>" } val italic: (String) -> String = { "<i>$it</i>" } val boldItalic = bold compose italic val italicBold = bold forwardCompose italic Composition
86. val bold: (String) -> String = { "<b>$it</b>" } val italic: (String) -> String = { "<i>$it</i>" } val boldItalic = bold compose italic val italicBold = bold forwardCompose italic Composition // boldItalic(“Hello”)
87. val bold: (String) -> String = { "<b>$it</b>" } val italic: (String) -> String = { "<i>$it</i>" } val boldItalic = bold compose italic val italicBold = bold forwardCompose italic Composition // <b><i>Hello</i></b>
88. val bold: (String) -> String = { "<b>$it</b>" } val italic: (String) -> String = { "<i>$it</i>" } val boldItalic = bold compose italic val italicBold = bold forwardCompose italic Composition
89. val bold: (String) -> String = { "<b>$it</b>" } val italic: (String) -> String = { "<i>$it</i>" } val boldItalic = bold compose italic val italicBold = bold forwardCompose italic Composition // italicBold(“Hello”)
90. val bold: (String) -> String = { "<b>$it</b>" } val italic: (String) -> String = { "<i>$it</i>" } val boldItalic = bold compose italic val italicBold = bold forwardCompose italic Composition // <i><b>Hello</b></i>
91. val bold: (String) -> String = { "<b>$it</b>" } val italic: (String) -> String = { "<i>$it</i>" } val boldItalic = bold compose italic val italicBold = bold forwardCompose italic Composition
92. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
93. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
94. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
95. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
96. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
97. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
98. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
99. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
100. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application // x2(10)
101. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application // 20
102. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
103. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
104. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
105. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
106. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
107. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
108. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application // x5(10)
109. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application // 50
110. fun multiply(a: Int, b: Int): Int = a * b val x2: (Int) -> Int = ::multiply.partially1(2) val x5: (Int) -> Int = ::multiply.partially1(5) Partial Application
111. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
112. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
113. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
114. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
115. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
116. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
117. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
118. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
119. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
120. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
121. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
122. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
123. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
124. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
125. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
126. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog } // findCat(animals)
127. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
128. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
129. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
130. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
131. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
132. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
133. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog } // findDog(animals)
134. Reverse fun findFirst( animals: List<Animal>, predicate: (Animal) -> Boolean ): Option<Animal> { /* … */ } val findCat: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Cat } val findDog: (List<Animal>) -> Option<Animal> = ::findFirst.reverse().partially1 { it is Dog }
135. Logical Complement val onlyCats: (Animal) -> Boolean = { it is Cat } val allCats = filter(animals, onlyCats) val noCats = onlyCats.complement() val allExceptCats = filter(animals, noCats)
136. Logical Complement val onlyCats: (Animal) -> Boolean = { it is Cat } val allCats = filter(animals, onlyCats) val noCats = onlyCats.complement() val allExceptCats = filter(animals, noCats)
137. Logical Complement val onlyCats: (Animal) -> Boolean = { it is Cat } val allCats = filter(animals, onlyCats) val noCats = onlyCats.complement() val allExceptCats = filter(animals, noCats)
138. Logical Complement val onlyCats: (Animal) -> Boolean = { it is Cat } val allCats = filter(animals, onlyCats) val noCats = onlyCats.complement() val allExceptCats = filter(animals, noCats)
139. Logical Complement val onlyCats: (Animal) -> Boolean = { it is Cat } val allCats = filter(animals, onlyCats) val noCats = onlyCats.complement() val allExceptCats = filter(animals, noCats)
140. Logical Complement val onlyCats: (Animal) -> Boolean = { it is Cat } val allCats = filter(animals, onlyCats) val noCats = onlyCats.complement() val allExceptCats = filter(animals, noCats)
141. Logical Complement val onlyCats: (Animal) -> Boolean = { it is Cat } val allCats = filter(animals, onlyCats) val noCats = onlyCats.complement() val allExceptCats = filter(animals, noCats)
142. Logical Complement val onlyCats: (Animal) -> Boolean = { it is Cat } val allCats = filter(animals, onlyCats) val noCats = onlyCats.complement() val allExceptCats = filter(animals, noCats)
143. Logical Complement val onlyCats: (Animal) -> Boolean = { it is Cat } val allCats = filter(animals, onlyCats) val noCats = onlyCats.complement() val allExceptCats = filter(animals, noCats)
144. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
145. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
146. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
147. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
148. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
149. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
150. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
151. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1) // 100
152. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
153. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
154. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
155. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
156. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
157. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
158. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
159. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
160. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1) // 100
161. Currying (1/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length volume(10, 10, 1) val curriedVolume: (width: Int) -> (height: Int) -> (length: Int) -> Int = ::volume.curried() curriedVolume(10)(10)(1)
162. Currying (2/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length val area = ::volume .reverse().curried()(1) .uncurried().reverse() area(10, 10)
163. Currying (2/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length val area = ::volume .reverse().curried()(1) .uncurried().reverse() area(10, 10)
164. Currying (2/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length val area = ::volume .reverse().curried()(1) .uncurried().reverse() area(10, 10)
165. Currying (2/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length val area = ::volume .reverse().curried()(1) .uncurried().reverse() area(10, 10) // (width, height, length)
166. Currying (2/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length val area = ::volume .reverse().curried()(1) .uncurried().reverse() area(10, 10) // (length, height, width)
167. Currying (2/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length val area = ::volume .reverse().curried()(1) .uncurried().reverse() area(10, 10) // (length) -> (height) -> (width)
168. Currying (2/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length val area = ::volume .reverse().curried()(1) .uncurried().reverse() area(10, 10) // (height) -> (width)
169. Currying (2/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length val area = ::volume .reverse().curried()(1) .uncurried().reverse() area(10, 10) // (height, width)
170. Currying (2/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length val area = ::volume .reverse().curried()(1) .uncurried().reverse() area(10, 10) // (width, height)
171. Currying (2/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length val area = ::volume .reverse().curried()(1) .uncurried().reverse() area(10, 10)
172. Currying (2/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length val area = ::volume .reverse().curried()(1) .uncurried().reverse() area(10, 10)
173. Currying (2/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length val area = ::volume .reverse().curried()(1) .uncurried().reverse() area(10, 10) // 100
174. Currying (2/2) fun volume(width: Int, height: Int, length: Int): Int = width * height * length val area = ::volume .reverse().curried()(1) .uncurried().reverse() area(10, 10)
175. More… • memoize() // FunctionN • firstOption() // Array, Sequence, and Iterable • flatten() - tail() - prependTo(List<T>) // List • plus(C) // TupleN • paired() - tripled() // FunctionN • pipe() // FunctionN
176. Data Types compile “io.arrow-kt:arrow-core-data:$arrow_version”
177. Data Types • Option • Either • Try • Validated • Eval
178. Option sealed class Option<out A> { object None : Option<Nothing>() data class Some<out T>(val t: T) : Option<T>() } Option is an Algebraic Data Type that is used to model the absence of value. In Kotlin they are encoded with sealed class hierarchies.
179. Option sealed class Option<out A> { object None : Option<Nothing>() data class Some<out T>(val t: T) : Option<T>() } Option is an Algebraic Data Type that is used to model the absence of value. In Kotlin they are encoded with sealed class hierarchies.
180. Option sealed class Option<out A> { object None : Option<Nothing>() data class Some<out T>(val t: T) : Option<T>() } Option is an Algebraic Data Type that is used to model the absence of value. In Kotlin they are encoded with sealed class hierarchies.
181. Option sealed class Option<out A> { object None : Option<Nothing>() data class Some<out T>(val t: T) : Option<T>() } Option is an Algebraic Data Type that is used to model the absence of value. In Kotlin they are encoded with sealed class hierarchies.
182. Option sealed class Option<out A> { object None : Option<Nothing>() data class Some<out T>(val t: T) : Option<T>() } Option is an Algebraic Data Type that is used to model the absence of value. In Kotlin they are encoded with sealed class hierarchies.
183. Option (Construction) val intOption: Option<Int> = Option(1) val intOption: Option<Int> = None val intOption: Option<Int> = Option.fromNullable(a) // a: Int? val intOption: Option<Int> = 1.some() val intOption: Option<Int> = none()
184. Option (Construction) val intOption: Option<Int> = Option(1) val intOption: Option<Int> = None val intOption: Option<Int> = Option.fromNullable(a) // a: Int? val intOption: Option<Int> = 1.some() val intOption: Option<Int> = none()
185. Option (Construction) val intOption: Option<Int> = Option(1) val intOption: Option<Int> = None val intOption: Option<Int> = Option.fromNullable(a) // a: Int? val intOption: Option<Int> = 1.some() val intOption: Option<Int> = none()
186. Option (Construction) val intOption: Option<Int> = Option(1) val intOption: Option<Int> = None val intOption: Option<Int> = Option.fromNullable(a) // a: Int? val intOption: Option<Int> = 1.some() val intOption: Option<Int> = none()
187. Option (Construction) val intOption: Option<Int> = Option(1) val intOption: Option<Int> = None val intOption: Option<Int> = Option.fromNullable(a) // a: Int? val intOption: Option<Int> = 1.some() val intOption: Option<Int> = none()
188. Option (Construction) val intOption: Option<Int> = Option(1) val intOption: Option<Int> = None val intOption: Option<Int> = Option.fromNullable(a) // a: Int? val intOption: Option<Int> = 1.some() val intOption: Option<Int> = none()
189. Option (Construction) val intOption: Option<Int> = Option(1) val intOption: Option<Int> = None val intOption: Option<Int> = Option.fromNullable(a) // a: Int? val intOption: Option<Int> = 1.some() val intOption: Option<Int> = none()
190. Option (Extraction) val intOption: Option<Int> = Option(1) val nullableResult: Int? = intOption.orNull() val result: Int = intOption.getOrElse { 0 }
191. Option (Extraction) val intOption: Option<Int> = Option(1) val nullableResult: Int? = intOption.orNull() val result: Int = intOption.getOrElse { 0 }
192. Option (Extraction) val intOption: Option<Int> = Option(1) val nullableResult: Int? = intOption.orNull() val result: Int = intOption.getOrElse { 0 }
193. Option (Extraction) val intOption: Option<Int> = Option(1) val nullableResult: Int? = intOption.orNull() val result: Int = intOption.getOrElse { 0 }
194. Option (Extraction) val intOption: Option<Int> = Option(1) val nullableResult: Int? = intOption.orNull() val result: Int = intOption.getOrElse { 0 }
195. Option (Extraction - when) val intOption: Option<Int> = Option(1) when (intOption) { is None -> 0 is Some -> intOption.t } // Some(1)
196. Option (Extraction - when) val intOption: Option<Int> = Option(1) when (intOption) { is None -> 0 is Some -> intOption.t } // Some(1)
197. Option (Extraction - when) val intOption: Option<Int> = Option(1) when (intOption) { is None -> 0 is Some -> intOption.t } // Some(1)
198. Option (Extraction - when) val intOption: Option<Int> = Option(1) when (intOption) { is None -> 0 is Some -> intOption.t } // Some(1)
199. Option (Extraction - when) val intOption: Option<Int> = Option(1) when (intOption) { is None -> 0 is Some -> intOption.t } // Some(1)
200. Option (Extraction - when) val intOption: Option<Int> = Option(1) when (intOption) { is None -> 0 is Some -> intOption.t } // Some(1)
201. Option (Extraction - when) val intOption: Option<Int> = Option(1) when (intOption) { is None -> 0 is Some -> intOption.t } // Some(1)
202. Option (Extraction - fold) val intOption: Option<Int> = Option(1) intOption.fold( { 0 }, { it + 1 } ) // Some(2)
203. Option (Extraction - fold) val intOption: Option<Int> = Option(1) intOption.fold( { 0 }, { it + 1 } ) // Some(2)
204. Option (Extraction - fold) val intOption: Option<Int> = Option(1) intOption.fold( { 0 }, { it + 1 } ) // Some(2)
205. Option (Extraction - fold) val intOption: Option<Int> = Option(1) intOption.fold( { 0 }, { it + 1 } ) // Some(2)
206. Option (Extraction - fold) val intOption: Option<Int> = Option(1) intOption.fold( { 0 }, { it + 1 } ) // Some(2)
207. Option (Extraction - fold) val intOption: Option<Int> = Option(1) intOption.fold( { 0 }, { it + 1 } ) // Some(2)
208. Option (Extraction - fold) val intOption: Option<Int> = Option(1) intOption.fold( { 0 }, { it + 1 } ) // Some(2)
209. Option (map) val intOption: Option<Int> = Option(1) intOption.map { it * 2 } // Some(2) val intOption: Option<Int> = None intOption.map { it * 2 } // None
210. Option (map) val intOption: Option<Int> = Option(1) intOption.map { it * 2 } // Some(2) val intOption: Option<Int> = None intOption.map { it * 2 } // None
211. Option (map) val intOption: Option<Int> = Option(1) intOption.map { it * 2 } // Some(2) val intOption: Option<Int> = None intOption.map { it * 2 } // None
212. Option (map) val intOption: Option<Int> = Option(1) intOption.map { it * 2 } // Some(2) val intOption: Option<Int> = None intOption.map { it * 2 } // None
213. Option (map) val intOption: Option<Int> = Option(1) intOption.map { it * 2 } // Some(2) val intOption: Option<Int> = None intOption.map { it * 2 } // None
214. Option (map) val intOption: Option<Int> = Option(1) intOption.map { it * 2 } // Some(2) val intOption: Option<Int> = None intOption.map { it * 2 } // None
215. Option (map) val intOption: Option<Int> = Option(1) intOption.map { it * 2 } // Some(2) val intOption: Option<Int> = None intOption.map { it * 2 } // None
216. Option (map) val intOption: Option<Int> = Option(1) intOption.map { it * 2 } // Some(2) val intOption: Option<Int> = None intOption.map { it * 2 } // None
217. Option (flatMap) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) oneOption.flatMap { one -> twoOption.map { two -> one + two } } // Some(3)
218. Option (flatMap) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) oneOption.flatMap { one -> twoOption.map { two -> one + two } } // Some(3)
219. Option (flatMap) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) oneOption.flatMap { one -> twoOption.map { two -> one + two } } // Some(3)
220. Option (flatMap) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) oneOption.flatMap { one -> twoOption.map { two -> one + two } } // Some(3)
221. Option (flatMap) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) oneOption.flatMap { one -> twoOption.map { two -> one + two } } // Some(3)
222. Option (flatMap) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) oneOption.flatMap { one -> twoOption.map { two -> one + two } } // Some(3)
223. Option (flatMap) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) oneOption.flatMap { one -> twoOption.map { two -> one + two } } // Some(3)
224. Option (flatMap) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = None oneOption.flatMap { one -> twoOption.map { two -> one + two } } // None
225. Option (flatMap) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = None oneOption.flatMap { one -> twoOption.map { two -> one + two } } // None
226. Option (flatMap) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = None oneOption.flatMap { one -> twoOption.map { two -> one + two } } // None
227. Option (Monad Binding) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) Option.monad().binding { val one = oneOption.bind() val two = twoOption.bind() one + two }.fix() // Some(3)
228. Option (Monad Binding) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) Option.monad().binding { val one = oneOption.bind() val two = twoOption.bind() one + two }.fix() // Some(3)
229. Option (Monad Binding) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) Option.monad().binding { val one = oneOption.bind() val two = twoOption.bind() one + two }.fix() // Some(3)
230. Option (Monad Binding) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) Option.monad().binding { val one = oneOption.bind() val two = twoOption.bind() one + two }.fix() // Some(3)
231. Option (Monad Binding) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) Option.monad().binding { val one = oneOption.bind() val two = twoOption.bind() one + two }.fix() // Some(3)
232. Option (Monad Binding) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) Option.monad().binding { val one = oneOption.bind() val two = twoOption.bind() one + two }.fix() // Some(3)
233. Option (Monad Binding) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) Option.monad().binding { val one = oneOption.bind() val two = twoOption.bind() one + two }.fix() // Some(3)
234. Option (Monad Binding) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) Option.monad().binding { val one = oneOption.bind() val two = twoOption.bind() one + two }.fix() // Some(3)
235. Option (Monad Binding) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = Option(2) Option.monad().binding { val one = oneOption.bind() val two = twoOption.bind() one + two }.fix() // Some(3)
236. Option (Monad Binding) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = None Option.monad().binding { val one = oneOption.bind() val two = twoOption.bind() one + two }.fix() // None
237. Option (Monad Binding) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = None Option.monad().binding { val one = oneOption.bind() val two = twoOption.bind() one + two }.fix() // None
238. Option (Monad Binding) val oneOption: Option<Int> = Option(1) val twoOption: Option<Int> = None Option.monad().binding { val one = oneOption.bind() val two = twoOption.bind() one + two }.fix() // None
239. Option (Applicative Builder) val maybeEspresso: Option<Espresso> = Option(Espresso(0.3)) val maybeMilkOption: Option<Milk> = Option(Milk(0.3)) val foamOption: Option<Foam> = Option(Foam(0.3)) Option.applicative() .map(maybeEspresso, maybeMilk, maybeFoam) { (espresso, milk, foam) -> Cappuccino(espresso, milk, foam) }.fix() // Some(Cappuccino(espresso=Espresso(%=0.3), milk=Milk(%=0.3), // foam=Foam(%=0.3)))
240. Option (Applicative Builder) val maybeEspresso: Option<Espresso> = Option(Espresso(0.3)) val maybeMilkOption: Option<Milk> = Option(Milk(0.3)) val foamOption: Option<Foam> = Option(Foam(0.3)) Option.applicative() .map(maybeEspresso, maybeMilk, maybeFoam) { (espresso, milk, foam) -> Cappuccino(espresso, milk, foam) }.fix() // Some(Cappuccino(espresso=Espresso(%=0.3), milk=Milk(%=0.3), // foam=Foam(%=0.3)))
241. Option (Applicative Builder) val maybeEspresso: Option<Espresso> = Option(Espresso(0.3)) val maybeMilkOption: Option<Milk> = Option(Milk(0.3)) val foamOption: Option<Foam> = Option(Foam(0.3)) Option.applicative() .map(maybeEspresso, maybeMilk, maybeFoam) { (espresso, milk, foam) -> Cappuccino(espresso, milk, foam) }.fix() // Some(Cappuccino(espresso=Espresso(%=0.3), milk=Milk(%=0.3), // foam=Foam(%=0.3)))
242. Option (Applicative Builder) val maybeEspresso: Option<Espresso> = Option(Espresso(0.3)) val maybeMilkOption: Option<Milk> = Option(Milk(0.3)) val foamOption: Option<Foam> = Option(Foam(0.3)) Option.applicative() .map(maybeEspresso, maybeMilk, maybeFoam) { (espresso, milk, foam) -> Cappuccino(espresso, milk, foam) }.fix() // Some(Cappuccino(espresso=Espresso(%=0.3), milk=Milk(%=0.3), // foam=Foam(%=0.3)))
243. Option (Applicative Builder) val maybeEspresso: Option<Espresso> = Option(Espresso(0.3)) val maybeMilkOption: Option<Milk> = Option(Milk(0.3)) val foamOption: Option<Foam> = Option(Foam(0.3)) Option.applicative() .map(maybeEspresso, maybeMilk, maybeFoam) { (espresso, milk, foam) -> Cappuccino(espresso, milk, foam) }.fix() // Some(Cappuccino(espresso=Espresso(%=0.3), milk=Milk(%=0.3), // foam=Foam(%=0.3)))
244. Option (Applicative Builder) val maybeEspresso: Option<Espresso> = Option(Espresso(0.3)) val maybeMilkOption: Option<Milk> = Option(Milk(0.3)) val foamOption: Option<Foam> = Option(Foam(0.3)) Option.applicative() .map(maybeEspresso, maybeMilk, maybeFoam) { (espresso, milk, foam) -> Cappuccino(espresso, milk, foam) }.fix() // Some(Cappuccino(espresso=Espresso(%=0.3), milk=Milk(%=0.3), // foam=Foam(%=0.3)))
245. Option (Applicative Builder) val maybeEspresso: Option<Espresso> = Option(Espresso(0.3)) val maybeMilkOption: Option<Milk> = Option(Milk(0.3)) val foamOption: Option<Foam> = Option(Foam(0.3)) Option.applicative() .map(maybeEspresso, maybeMilk, maybeFoam) { (espresso, milk, foam) -> Cappuccino(espresso, milk, foam) }.fix() // Some(Cappuccino(espresso=Espresso(%=0.3), milk=Milk(%=0.3), // foam=Foam(%=0.3)))
246. Option (Applicative Builder) val maybeEspresso: Option<Espresso> = Option(Espresso(0.3)) val maybeMilkOption: Option<Milk> = Option(Milk(0.3)) val foamOption: Option<Foam> = Option(Foam(0.3)) Option.applicative() .map(maybeEspresso, maybeMilk, maybeFoam) { (espresso, milk, foam) -> Cappuccino(espresso, milk, foam) }.fix() // Some(Cappuccino(espresso=Espresso(%=0.3), milk=Milk(%=0.3), // foam=Foam(%=0.3)))
247. Option (Applicative Builder) val maybeEspresso: Option<Espresso> = Option(Espresso(0.3)) val maybeMilkOption: Option<Milk> = Option(Milk(0.3)) val foamOption: Option<Foam> = Option(Foam(0.3)) Option.applicative() .map(maybeEspresso, maybeMilk, maybeFoam) { (espresso, milk, foam) -> Cappuccino(espresso, milk, foam) }.fix() // Some(Cappuccino(espresso=Espresso(%=0.3), milk=Milk(%=0.3), // foam=Foam(%=0.3)))
248. Option (Applicative Builder) val maybeEspresso: Option<Espresso> = Option(Espresso(0.3)) val maybeMilkOption: Option<Milk> = Option(Milk(0.3)) val foamOption: Option<Foam> = Option(Foam(0.3)) Option.applicative() .map(maybeEspresso, maybeMilk, maybeFoam) { (espresso, milk, foam) -> Cappuccino(espresso, milk, foam) }.fix() // Some(Cappuccino(espresso=Espresso(%=0.3), milk=Milk(%=0.3), // foam=Foam(%=0.3)))
249. Option (Applicative Builder) val maybeEspresso: Option<Espresso> = Option(Espresso(0.3)) val maybeMilkOption: Option<Milk> = Option(Milk(0.3)) val foamOption: Option<Foam> = Option(Foam(0.3)) Option.applicative() .map(maybeEspresso, maybeMilk, maybeFoam) { (espresso, milk, foam) -> Cappuccino(espresso, milk, foam) }.fix() // Some(Cappuccino(espresso=Espresso(%=0.3), milk=Milk(%=0.3), // foam=Foam(%=0.3)))
250. Option (Applicative Builder) val maybeEspresso: Option<Espresso> = Option(Espresso(0.3)) val maybeMilkOption: Option<Milk> = Option(Milk(0.3)) val foamOption: Option<Foam> = None Option.applicative() .map(maybeEspresso, maybeMilk, maybeFoam) { (espresso, milk, foam) -> Cappuccino(espresso, milk, foam) }.fix() // None
251. Option (Applicative Builder) val maybeEspresso: Option<Espresso> = Option(Espresso(0.3)) val maybeMilkOption: Option<Milk> = Option(Milk(0.3)) val foamOption: Option<Foam> = None Option.applicative() .map(maybeEspresso, maybeMilk, maybeFoam) { (espresso, milk, foam) -> Cappuccino(espresso, milk, foam) }.fix() // None
252. Option (Applicative Builder) val maybeEspresso: Option<Espresso> = Option(Espresso(0.3)) val maybeMilkOption: Option<Milk> = Option(Milk(0.3)) val foamOption: Option<Foam> = None Option.applicative() .map(maybeEspresso, maybeMilk, maybeFoam) { (espresso, milk, foam) -> Cappuccino(espresso, milk, foam) }.fix() // None
253. Either sealed class Either<out A, out B> { data class Left<out A, out B>(val a: A) : Either<A, B>() data class Right<out A, out B>(val b: B) : Either<A, B>() } Either is an Algebraic Data Type that is used to model a return type that may return one of two possible values.
254. Either sealed class Either<out A, out B> { data class Left<out A, out B>(val a: A) : Either<A, B>() data class Right<out A, out B>(val b: B) : Either<A, B>() } Either is an Algebraic Data Type that is used to model a return type that may return one of two possible values.
255. Either sealed class Either<out A, out B> { data class Left<out A, out B>(val a: A) : Either<A, B>() data class Right<out A, out B>(val b: B) : Either<A, B>() } Either is an Algebraic Data Type that is used to model a return type that may return one of two possible values.
256. Either sealed class Either<out A, out B> { data class Left<out A, out B>(val a: A) : Either<A, B>() data class Right<out A, out B>(val b: B) : Either<A, B>() } Either is an Algebraic Data Type that is used to model a return type that may return one of two possible values.
257. Either sealed class Either<out A, out B> { data class Left<out A, out B>(val a: A) : Either<A, B>() data class Right<out A, out B>(val b: B) : Either<A, B>() } Either is an Algebraic Data Type that is used to model a return type that may return one of two possible values.
258. Either (Construction) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) val result: Either<DomainError, Int> = Left(UnknownUser) val result: Either<DomainError, Int> = 1.right() val result: Either<DomainError, Int> = UnknownUser.left()
259. Either (Construction) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) val result: Either<DomainError, Int> = Left(UnknownUser) val result: Either<DomainError, Int> = 1.right() val result: Either<DomainError, Int> = UnknownUser.left()
260. Either (Construction) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) val result: Either<DomainError, Int> = Left(UnknownUser) val result: Either<DomainError, Int> = 1.right() val result: Either<DomainError, Int> = UnknownUser.left()
261. Either (Construction) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) val result: Either<DomainError, Int> = Left(UnknownUser) val result: Either<DomainError, Int> = 1.right() val result: Either<DomainError, Int> = UnknownUser.left()
262. Either (Construction) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) val result: Either<DomainError, Int> = Left(UnknownUser) val result: Either<DomainError, Int> = 1.right() val result: Either<DomainError, Int> = UnknownUser.left()
263. Either (Construction) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) val result: Either<DomainError, Int> = Left(UnknownUser) val result: Either<DomainError, Int> = 1.right() val result: Either<DomainError, Int> = UnknownUser.left()
264. Either (Construction) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) val result: Either<DomainError, Int> = Left(UnknownUser) val result: Either<DomainError, Int> = 1.right() val result: Either<DomainError, Int> = UnknownUser.left()
265. Either (Extraction - when) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) when (result) { is Left -> 0 is Right -> result.b } // Right(1)
266. Either (Extraction - when) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) when (result) { is Left -> 0 is Right -> result.b } // Right(1)
267. Either (Extraction - when) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) when (result) { is Left -> 0 is Right -> result.b } // Right(1)
268. Either (Extraction - when) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) when (result) { is Left -> 0 is Right -> result.b } // Right(1)
269. Either (Extraction - when) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) when (result) { is Left -> 0 is Right -> result.b } // Right(1) F
270. Either (Extraction - when) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) when (result) { is Left -> 0 is Right -> result.b } // Right(1)
271. Either (Extraction - when) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) when (result) { is Left -> 0 is Right -> result.b } // Right(1)
272. Either (Extraction - fold) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.fold( { 0 }, { it + 1 } ) // Right(2)
273. Either (Extraction - fold) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.fold( { 0 }, { it + 1 } ) // Right(2)
274. Either (Extraction - fold) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.fold( { 0 }, { it + 1 } ) // Right(2)
275. Either (Extraction - fold) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.fold( { 0 }, { it + 1 } ) // Right(2)
276. Either (Extraction - fold) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.fold( { 0 }, { it + 1 } ) // Right(2)
277. Either (Extraction - fold) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.fold( { 0 }, { it + 1 } ) // Right(2)
278. Either (Extraction - fold) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.fold( { 0 }, { it + 1 } ) // Right(2)
279. Either (map) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.map { it * 2 } // Right(2) val result: Either<DomainError, Int> = Left(UnknownUser) result.map { it * 2 } // Left(UnknownUser)
280. Either (map) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.map { it * 2 } // Right(2) val result: Either<DomainError, Int> = Left(UnknownUser) result.map { it * 2 } // Left(UnknownUser)
281. Either (map) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.map { it * 2 } // Right(2) val result: Either<DomainError, Int> = Left(UnknownUser) result.map { it * 2 } // Left(UnknownUser)
282. Either (map) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.map { it * 2 } // Right(2) val result: Either<DomainError, Int> = Left(UnknownUser) result.map { it * 2 } // Left(UnknownUser)
283. Either (map) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.map { it * 2 } // Right(2) val result: Either<DomainError, Int> = Left(UnknownUser) result.map { it * 2 } // Left(UnknownUser)
284. Either (map) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.map { it * 2 } // Right(2) val result: Either<DomainError, Int> = Left(UnknownUser) result.map { it * 2 } // Left(UnknownUser)
285. Either (map) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.map { it * 2 } // Right(2) val result: Either<DomainError, Int> = Left(UnknownUser) result.map { it * 2 } // Left(UnknownUser)
286. Either (map) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.map { it * 2 } // Right(2) val result: Either<DomainError, Int> = Left(UnknownUser) result.map { it * 2 } // Left(UnknownUser)
287. Either (map) sealed class DomainError { /* ... */ } val result: Either<DomainError, Int> = Right(1) result.map { it * 2 } // Right(2) val result: Either<DomainError, Int> = Left(UnknownUser) result.map { it * 2 } // Left(UnknownUser)
288. Either (flatMap) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) result1.flatMap { one -> result2.map { two -> one + two } } // Right(3)
289. Either (flatMap) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) result1.flatMap { one -> result2.map { two -> one + two } } // Right(3)
290. Either (flatMap) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) result1.flatMap { one -> result2.map { two -> one + two } } // Right(3)
291. Either (flatMap) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) result1.flatMap { one -> result2.map { two -> one + two } } // Right(3)
292. Either (flatMap) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) result1.flatMap { one -> result2.map { two -> one + two } } // Right(3)
293. Either (flatMap) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) result1.flatMap { one -> result2.map { two -> one + two } } // Right(3)
294. Either (flatMap) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) result1.flatMap { one -> result2.map { two -> one + two } } // Right(3)
295. Either (flatMap) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Left(UnknownUser) result1.flatMap { one -> result2.map { two -> one + two } } // Left(UnknownUser)
296. Either (flatMap) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Left(UnknownUser) result1.flatMap { one -> result2.map { two -> one + two } } // Left(UnknownUser)
297. Either (flatMap) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Left(UnknownUser) result1.flatMap { one -> result2.map { two -> one + two } } // Left(UnknownUser)
298. Either (Monad Binding) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) Either.monad<DomainError>.binding { val one = result1.bind() val two = result2.bind() one + two }.fix() // Right(3)
299. Either (Monad Binding) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) Either.monad<DomainError>.binding { val one = result1.bind() val two = result2.bind() one + two }.fix() // Right(3)
300. Either (Monad Binding) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) Either.monad<DomainError>.binding { val one = result1.bind() val two = result2.bind() one + two }.fix() // Right(3)
301. Either (Monad Binding) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) Either.monad<DomainError>.binding { val one = result1.bind() val two = result2.bind() one + two }.fix() // Right(3)
302. Either (Monad Binding) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) Either.monad<DomainError>.binding { val one = result1.bind() val two = result2.bind() one + two }.fix() // Right(3)
303. Either (Monad Binding) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) Either.monad<DomainError>.binding { val one = result1.bind() val two = result2.bind() one + two }.fix() // Right(3)
304. Either (Monad Binding) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) Either.monad<DomainError>.binding { val one = result1.bind() val two = result2.bind() one + two }.fix() // Right(3)
305. Either (Monad Binding) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) Either.monad<DomainError>.binding { val one = result1.bind() val two = result2.bind() one + two }.fix() // Right(3)
306. Either (Monad Binding) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Right(2) Either.monad<DomainError>.binding { val one = result1.bind() val two = result2.bind() one + two }.fix() // Right(3)
307. Either (Monad Binding) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Left(UnknownUser) Either.monad<DomainError>.binding { val one = result1.bind() val two = result2.bind() one + two }.fix() // Left(UnknownUser)
308. Either (Monad Binding) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Left(UnknownUser) Either.monad<DomainError>.binding { val one = result1.bind() val two = result2.bind() one + two }.fix() // Left(UnknownUser)
309. Either (Monad Binding) sealed class DomainError { /* ... */ } val result1: Either<DomainError, Int> = Right(1) val result2: Either<DomainError, Int> = Left(UnknownUser) Either.monad<DomainError>.binding { val one = result1.bind() val two = result2.bind() one + two }.fix() // Left(UnknownUser)
310. Either (Applicative Builder) sealed class CoffeeMakerError { /* ... */ } val espressoResult: Either<CoffeeMakerError, Espresso> = Right(Espresso(0.4)) val waterResult: Either<CoffeeMakerError, Water> = Right(Water(0.6)) Either.applicative<CoffeeMakerError>() .map(espressoResult, waterResult) { (espresso, water) -> Americano(espresso, water) }.fix() // Right(Americano(espresso=Espresso(%=0.4), water=Water(%=0.6)))
311. Either (Applicative Builder) sealed class CoffeeMakerError { /* ... */ } val espressoResult: Either<CoffeeMakerError, Espresso> = Right(Espresso(0.4)) val waterResult: Either<CoffeeMakerError, Water> = Right(Water(0.6)) Either.applicative<CoffeeMakerError>() .map(espressoResult, waterResult) { (espresso, water) -> Americano(espresso, water) }.fix() // Right(Americano(espresso=Espresso(%=0.4), water=Water(%=0.6)))
312. Either (Applicative Builder) sealed class CoffeeMakerError { /* ... */ } val espressoResult: Either<CoffeeMakerError, Espresso> = Right(Espresso(0.4)) val waterResult: Either<CoffeeMakerError, Water> = Right(Water(0.6)) Either.applicative<CoffeeMakerError>() .map(espressoResult, waterResult) { (espresso, water) -> Americano(espresso, water) }.fix() // Right(Americano(espresso=Espresso(%=0.4), water=Water(%=0.6)))
313. Either (Applicative Builder) sealed class CoffeeMakerError { /* ... */ } val espressoResult: Either<CoffeeMakerError, Espresso> = Right(Espresso(0.4)) val waterResult: Either<CoffeeMakerError, Water> = Right(Water(0.6)) Either.applicative<CoffeeMakerError>() .map(espressoResult, waterResult) { (espresso, water) -> Americano(espresso, water) }.fix() // Right(Americano(espresso=Espresso(%=0.4), water=Water(%=0.6)))
314. Either (Applicative Builder) sealed class CoffeeMakerError { /* ... */ } val espressoResult: Either<CoffeeMakerError, Espresso> = Right(Espresso(0.4)) val waterResult: Either<CoffeeMakerError, Water> = Right(Water(0.6)) Either.applicative<CoffeeMakerError>() .map(espressoResult, waterResult) { (espresso, water) -> Americano(espresso, water) }.fix() // Right(Americano(espresso=Espresso(%=0.4), water=Water(%=0.6)))
315. Either (Applicative Builder) sealed class CoffeeMakerError { /* ... */ } val espressoResult: Either<CoffeeMakerError, Espresso> = Right(Espresso(0.4)) val waterResult: Either<CoffeeMakerError, Water> = Right(Water(0.6)) Either.applicative<CoffeeMakerError>() .map(espressoResult, waterResult) { (espresso, water) -> Americano(espresso, water) }.fix() // Right(Americano(espresso=Espresso(%=0.4), water=Water(%=0.6)))
316. Either (Applicative Builder) sealed class CoffeeMakerError { /* ... */ } val espressoResult: Either<CoffeeMakerError, Espresso> = Right(Espresso(0.4)) val waterResult: Either<CoffeeMakerError, Water> = Right(Water(0.6)) Either.applicative<CoffeeMakerError>() .map(espressoResult, waterResult) { (espresso, water) -> Americano(espresso, water) }.fix() // Right(Americano(espresso=Espresso(%=0.4), water=Water(%=0.6)))
317. Either (Applicative Builder) sealed class CoffeeMakerError { /* ... */ } val espressoResult: Either<CoffeeMakerError, Espresso> = Right(Espresso(0.4)) val waterResult: Either<CoffeeMakerError, Water> = Right(Water(0.6)) Either.applicative<CoffeeMakerError>() .map(espressoResult, waterResult) { (espresso, water) -> Americano(espresso, water) }.fix() // Right(Americano(espresso=Espresso(%=0.4), water=Water(%=0.6)))
318. Either (Applicative Builder) sealed class CoffeeMakerError { /* ... */ } val espressoResult: Either<CoffeeMakerError, Espresso> = Right(Espresso(0.4)) val waterResult: Either<CoffeeMakerError, Water> = Right(Water(0.6)) Either.applicative<CoffeeMakerError>() .map(espressoResult, waterResult) { (espresso, water) -> Americano(espresso, water) }.fix() // Right(Americano(espresso=Espresso(%=0.4), water=Water(%=0.6)))
319. Either (Applicative Builder) sealed class CoffeeMakerError { /* ... */ } val espressoResult: Either<CoffeeMakerError, Espresso> = Right(Espresso(0.4)) val waterResult: Either<CoffeeMakerError, Water> = Right(Water(0.6)) Either.applicative<CoffeeMakerError>() .map(espressoResult, waterResult) { (espresso, water) -> Americano(espresso, water) }.fix() // Right(Americano(espresso=Espresso(%=0.4), water=Water(%=0.6)))
320. Either (Applicative Builder) sealed class CoffeeMakerError { /* ... */ } val espressoResult: Either<CoffeeMakerError, Espresso> = Right(Espresso(0.4)) val waterResult: Either<CoffeeMakerError, Water> = Right(Water(0.6)) Either.applicative<CoffeeMakerError>() .map(espressoResult, waterResult) { (espresso, water) -> Americano(espresso, water) }.fix() // Right(Americano(espresso=Espresso(%=0.4), water=Water(%=0.6)))
321. Either (Applicative Builder) sealed class CoffeeMakerError { /* ... */ } val espressoResult: Either<CoffeeMakerError, Espresso> = Right(Espresso(0.4)) val waterResult: Either<CoffeeMakerError, Water> = Left(RefillWater) Either.applicative<CoffeeMakerError>() .map(espressoResult, waterResult) { (espresso, water) -> Americano(espresso, water) }.fix() // Left(RefillWater)
322. Either (Applicative Builder) sealed class CoffeeMakerError { /* ... */ } val espressoResult: Either<CoffeeMakerError, Espresso> = Right(Espresso(0.4)) val waterResult: Either<CoffeeMakerError, Water> = Left(RefillWater) Either.applicative<CoffeeMakerError>() .map(espressoResult, waterResult) { (espresso, water) -> Americano(espresso, water) }.fix() // Left(RefillWater)
323. Either (Applicative Builder) sealed class CoffeeMakerError { /* ... */ } val espressoResult: Either<CoffeeMakerError, Espresso> = Right(Espresso(0.4)) val waterResult: Either<CoffeeMakerError, Water> = Left(RefillWater) Either.applicative<CoffeeMakerError>() .map(espressoResult, waterResult) { (espresso, water) -> Americano(espresso, water) }.fix() // Left(RefillWater)
324. More… • Try // Success - Failure • Validated // Valid - Invalid • Eval // Now - Always - Later - Defer • TupleN // Tuple2 - Tuple22
325. Typeclasses compile “io.arrow-kt:arrow-typeclasses:$arrow_version” kapt “io.arrow-kt:arrow-meta:$arrow_version”
326. Typeclasses • Polymorphism in functional programming. • Separates data from behaviour. • Maybe governed by algebraic / category theoretic laws. • Implemented as interfaces in Kotlin. • One Typeclass instance per type.
327. Typeclasses • Show • Eq • Semigroup • Functor • Monad • …
328. Show interface Show<in A> { fun A.show(): String } The Show typeclass abstracts the ability to obtain a String representation of any object.
329. Show interface Show<in A> { fun A.show(): String } The Show typeclass abstracts the ability to obtain a String representation of any object.
330. Show interface Show<in A> { fun A.show(): String } The Show typeclass abstracts the ability to obtain a String representation of any object.
331. Show interface Show<in A> { fun A.show(): String } The Show typeclass abstracts the ability to obtain a String representation of any object.
332. Eq interface Eq<in F> { fun F.eqv(b: F): Boolean fun F.neqv(b: F): Boolean = !eqv(b) } The Eq typeclass abstracts the ability to compare two instances of any object. It can be compared to the typeclass equivalent of Java’s Object#equals.
333. Eq interface Eq<in F> { fun F.eqv(b: F): Boolean fun F.neqv(b: F): Boolean = !eqv(b) } The Eq typeclass abstracts the ability to compare two instances of any object. It can be compared to the typeclass equivalent of Java’s Object#equals.
334. Eq interface Eq<in F> { fun F.eqv(b: F): Boolean fun F.neqv(b: F): Boolean = !eqv(b) } The Eq typeclass abstracts the ability to compare two instances of any object. It can be compared to the typeclass equivalent of Java’s Object#equals.
335. Eq interface Eq<in F> { fun F.eqv(b: F): Boolean fun F.neqv(b: F): Boolean = !eqv(b) } The Eq typeclass abstracts the ability to compare two instances of any object. It can be compared to the typeclass equivalent of Java’s Object#equals.
336. Eq interface Eq<in F> { fun F.eqv(b: F): Boolean fun F.neqv(b: F): Boolean = !eqv(b) } The Eq typeclass abstracts the ability to compare two instances of any object. It can be compared to the typeclass equivalent of Java’s Object#equals.
337. Semigroup interface Semigroup<A> { fun A.combine(b: A): A operator fun A.plus(b: A): A = this.combine(b) } The Semigroup for some given type A has a single operation combine which takes two values of type A, and returns a value of type A. This operation must be associative.
338. Semigroup interface Semigroup<A> { fun A.combine(b: A): A operator fun A.plus(b: A): A = this.combine(b) } The Semigroup for some given type A has a single operation combine which takes two values of type A, and returns a value of type A. This operation must be associative.
339. Semigroup interface Semigroup<A> { fun A.combine(b: A): A operator fun A.plus(b: A): A = this.combine(b) } The Semigroup for some given type A has a single operation combine which takes two values of type A, and returns a value of type A. This operation must be associative.
340. Semigroup interface Semigroup<A> { fun A.combine(b: A): A operator fun A.plus(b: A): A = this.combine(b) } The Semigroup for some given type A has a single operation combine which takes two values of type A, and returns a value of type A. This operation must be associative.
341. Semigroup interface Semigroup<A> { fun A.combine(b: A): A operator fun A.plus(b: A): A = this.combine(b) } The Semigroup for some given type A has a single operation combine which takes two values of type A, and returns a value of type A. This operation must be associative.
342. Creating Instances data class Person(val firstName: String, val lastName: String) { companion object } @extension interface PersonShow : Show<Person> { override fun Person.show(): String = "$firstName $lastName" } val john = Person("John", "Doe") Person.show().run { john.show() } // John Doe
343. Creating Instances data class Person(val firstName: String, val lastName: String) { companion object } @extension interface PersonShow : Show<Person> { override fun Person.show(): String = "$firstName $lastName" } val john = Person("John", "Doe") Person.show().run { john.show() } // John Doe
344. Creating Instances data class Person(val firstName: String, val lastName: String) { companion object } @extension interface PersonShow : Show<Person> { override fun Person.show(): String = "$firstName $lastName" } val john = Person("John", "Doe") Person.show().run { john.show() } // John Doe
345. Creating Instances data class Person(val firstName: String, val lastName: String) { companion object } @extension interface PersonShow : Show<Person> { override fun Person.show(): String = "$firstName $lastName" } val john = Person("John", "Doe") Person.show().run { john.show() } // John Doe
346. Creating Instances data class Person(val firstName: String, val lastName: String) { companion object } @extension interface PersonShow : Show<Person> { override fun Person.show(): String = "$firstName $lastName" } val john = Person("John", "Doe") Person.show().run { john.show() } // John Doe
347. Creating Instances data class Person(val firstName: String, val lastName: String) { companion object } @extension interface PersonShow : Show<Person> { override fun Person.show(): String = "$firstName $lastName" } val john = Person("John", "Doe") Person.show().run { john.show() } // John Doe
348. Creating Instances data class Person(val firstName: String, val lastName: String) { companion object } @extension interface PersonShow : Show<Person> { override fun Person.show(): String = "$firstName $lastName" } val john = Person("John", "Doe") Person.show().run { john.show() } // John Doe
349. Creating Instances data class Person(val firstName: String, val lastName: String) { companion object } @extension interface PersonShow : Show<Person> { override fun Person.show(): String = "$firstName $lastName" } val john = Person("John", "Doe") Person.show().run { john.show() } // John Doe
350. Creating Instances data class Person(val firstName: String, val lastName: String) { companion object } @extension interface PersonShow : Show<Person> { override fun Person.show(): String = "$firstName $lastName" } val john = Person("John", "Doe") Person.show().run { john.show() } // John Doe
351. Creating Instances data class Person(val firstName: String, val lastName: String) { companion object } @extension interface PersonShow : Show<Person> { override fun Person.show(): String = "$firstName $lastName" } val john = Person("John", "Doe") Person.show().run { john.show() } // John Doe
352. Creating Instances data class Person(val firstName: String, val lastName: String) { companion object } @extension interface PersonShow : Show<Person> { override fun Person.show(): String = "$firstName $lastName" } val john = Person("John", "Doe") Person.show().run { john.show() } // John Doe
353. Creating Instances data class Person(val firstName: String, val lastName: String) { companion object } @extension interface PersonShow : Show<Person> { override fun Person.show(): String = "$firstName $lastName" } val john = Person("John", "Doe") Person.show().run { john.show() } // John Doe
354. More… • Hash • Order • Traverse • Applicative • And many more…
355. Optics compile “io.arrow-kt:arrow-optics:$arrow_version” kapt “io.arrow-kt:arrow-meta:$arrow_version”
356. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
357. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
358. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
359. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
360. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
361. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
362. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
363. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
364. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
365. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
366. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
367. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
368. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
369. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
370. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
371. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
372. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
373. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
374. Lens @optics data class UserProfile( val name: Name, /* Not shown for brevity */ val contact: Contact ) { companion object } @optics data class Contact( val email: String, val phone: String ) { companion object }
375. Without Lens val profile = UserProfile( Name("John", "Doe"), Contact("john.doe@personal.com", "6483920164") ) val updatedProfile = profile.copy( contact = profile.contact.copy( email = "john.doe@work.com" ) )
376. Without Lens val profile = UserProfile( Name("John", "Doe"), Contact("john.doe@personal.com", "6483920164") ) val updatedProfile = profile.copy( contact = profile.contact.copy( email = "john.doe@work.com" ) )
377. Without Lens val profile = UserProfile( Name("John", "Doe"), Contact("john.doe@personal.com", "6483920164") ) val updatedProfile = profile.copy( contact = profile.contact.copy( email = "john.doe@work.com" ) )
378. Without Lens val profile = UserProfile( Name("John", "Doe"), Contact("john.doe@personal.com", "6483920164") ) val updatedProfile = profile.copy( contact = profile.contact.copy( email = "john.doe@work.com" ) )
379. Without Lens val profile = UserProfile( Name("John", "Doe"), Contact("john.doe@personal.com", "6483920164") ) val updatedProfile = profile.copy( contact = profile.contact.copy( email = "john.doe@work.com" ) )
380. Without Lens val profile = UserProfile( Name("John", "Doe"), Contact("john.doe@personal.com", "6483920164") ) val updatedProfile = profile.copy( contact = profile.contact.copy( email = "john.doe@work.com" ) )
381. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
382. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
383. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
384. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
385. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
386. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
387. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
388. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
389. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
390. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
391. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
392. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
393. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
394. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
395. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
396. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile) // “john.doe@work.com”
397. With Lens val profile = UserProfile( /* … */ ) val emailLens: Lens<UserProfile, String> = UserProfile.contact.email val workEmail = "john.doe@work.com" val updatedProfile = emailLens.modify(profile) { workEmail } val email = emailLens.get(profile)
398. Optional @optics data class ShoppingCart( val id: String, val cartItems: ListK<CartItem> ) { companion object } @optics data class CartItem( val product: Product, /* Not shown for brevity */ val quantity: Int ) { companion object }
399. Optional @optics data class ShoppingCart( val id: String, val cartItems: ListK<CartItem> ) { companion object } @optics data class CartItem( val product: Product, /* Not shown for brevity */ val quantity: Int ) { companion object }
400. Optional @optics data class ShoppingCart( val id: String, val cartItems: ListK<CartItem> ) { companion object } @optics data class CartItem( val product: Product, /* Not shown for brevity */ val quantity: Int ) { companion object }
401. Optional @optics data class ShoppingCart( val id: String, val cartItems: ListK<CartItem> ) { companion object } @optics data class CartItem( val product: Product, /* Not shown for brevity */ val quantity: Int ) { companion object }
402. Optional @optics data class ShoppingCart( val id: String, val cartItems: ListK<CartItem> ) { companion object } @optics data class CartItem( val product: Product, /* Not shown for brevity */ val quantity: Int ) { companion object }
403. Optional @optics data class ShoppingCart( val id: String, val cartItems: ListK<CartItem> ) { companion object } @optics data class CartItem( val product: Product, /* Not shown for brevity */ val quantity: Int ) { companion object }
404. Optional @optics data class ShoppingCart( val id: String, val cartItems: ListK<CartItem> ) { companion object } @optics data class CartItem( val product: Product, /* Not shown for brevity */ val quantity: Int ) { companion object }
405. Optional (Set) val shoppingCart = ShoppingCart("CRT19321", cartItems) val quantityOptional: Optional<ShoppingCart, Int> = ShoppingCart .cartItems .index(ListK.index(), productIndex) .quantity val updatedCart = quantityOptional.modify(shoppingCart) { it + 1 }
406. Optional (Set) val shoppingCart = ShoppingCart("CRT19321", cartItems) val quantityOptional: Optional<ShoppingCart, Int> = ShoppingCart .cartItems .index(ListK.index(), productIndex) .quantity val updatedCart = quantityOptional.modify(shoppingCart) { it + 1 }
407. Optional (Set) val shoppingCart = ShoppingCart("CRT19321", cartItems) val quantityOptional: Optional<ShoppingCart, Int> = ShoppingCart .cartItems .index(ListK.index(), productIndex) .quantity val updatedCart = quantityOptional.modify(shoppingCart) { it + 1 }
408. Optional (Set) val shoppingCart = ShoppingCart("CRT19321", cartItems) val quantityOptional: Optional<ShoppingCart, Int> = ShoppingCart .cartItems .index(ListK.index(), productIndex) .quantity val updatedCart = quantityOptional.modify(shoppingCart) { it + 1 }
409. Optional (Set) val shoppingCart = ShoppingCart("CRT19321", cartItems) val quantityOptional: Optional<ShoppingCart, Int> = ShoppingCart .cartItems .index(ListK.index(), productIndex) .quantity val updatedCart = quantityOptional.modify(shoppingCart) { it + 1 }
410. Optional (Set) val shoppingCart = ShoppingCart("CRT19321", cartItems) val quantityOptional: Optional<ShoppingCart, Int> = ShoppingCart .cartItems .index(ListK.index(), productIndex) .quantity val updatedCart = quantityOptional.modify(shoppingCart) { it + 1 }
411. Optional (Set) val shoppingCart = ShoppingCart("CRT19321", cartItems) val quantityOptional: Optional<ShoppingCart, Int> = ShoppingCart .cartItems .index(ListK.index(), productIndex) .quantity val updatedCart = quantityOptional.modify(shoppingCart) { it + 1 }
412. Optional (Set) val shoppingCart = ShoppingCart("CRT19321", cartItems) val quantityOptional: Optional<ShoppingCart, Int> = ShoppingCart .cartItems .index(ListK.index(), productIndex) .quantity val updatedCart = quantityOptional.modify(shoppingCart) { it + 1 }
413. Optional (Set) val shoppingCart = ShoppingCart("CRT19321", cartItems) val quantityOptional: Optional<ShoppingCart, Int> = ShoppingCart .cartItems .index(ListK.index(), productIndex) .quantity val updatedCart = quantityOptional.modify(shoppingCart) { it + 1 }
414. Optional (Set) val shoppingCart = ShoppingCart("CRT19321", cartItems) val quantityOptional: Optional<ShoppingCart, Int> = ShoppingCart .cartItems .index(ListK.index(), productIndex) .quantity val updatedCart = quantityOptional.modify(shoppingCart) { it + 1 }
415. Optional (Set) val shoppingCart = ShoppingCart("CRT19321", cartItems) val quantityOptional: Optional<ShoppingCart, Int> = ShoppingCart .cartItems .index(ListK.index(), productIndex) .quantity val updatedCart = quantityOptional.modify(shoppingCart) { it + 1 }
416. Optional (Set) val shoppingCart = ShoppingCart("CRT19321", cartItems) val quantityOptional: Optional<ShoppingCart, Int> = ShoppingCart .cartItems .index(ListK.index(), productIndex) .quantity val updatedCart = quantityOptional.modify(shoppingCart) { it + 1 }
417. Optional (Set) val shoppingCart = ShoppingCart("CRT19321", cartItems) val quantityOptional: Optional<ShoppingCart, Int> = ShoppingCart .cartItems .index(ListK.index(), productIndex) .quantity val updatedCart = quantityOptional.modify(shoppingCart) { it + 1 }
418. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
419. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
420. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
421. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
422. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
423. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
424. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
425. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
426. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
427. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
428. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
429. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
430. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
431. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
432. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
433. Optional (Get) val cartItemOption = ShoppingCart .cartItems .index(ListK.index(), productIndex) .getOption(shoppingCart) val sameCartItemOption = ListK.index<CartItem>().run { ShoppingCart.cartItems[productIndex].getOption(shoppingCart) }
434. More… • Iso • Prism • Getter / Setter • Fold • Each • And others …
435. That’s not it… • Arrow Fx • Effects • Arrow Query Language • Generic • Integrations • Free • Recursion Schemes
436. Resources • https://arrow-kt.io/docs/ • http://learnyouahaskell.com/ • https://caster.io/courses/functional-programming-in-kotlin-with-arrow • https://github.com/hemanth/functional-programming-jargon#function • https://wiki.haskell.org/Typeclassopedia • http://nealford.com/functionalthinking.html • https://prod.packtpub.com/in/application-development/functional-kotlin
437. end; @ragunathjawahar Twitter / Medium / GitHub