Go Pure with ClojureScript

Transcript

1. Go Pure with ClojureScript
2. Marcelo Piva Software Engineer @ Nubank @mpivaa github.com/mpivaa instagram.com/m.pivaa
5. ?
6. ? Why
7. Consistency Predictability Safety
8. Consistency Predictability Safety
9. Consistency Predictability Safety
10. Immutability Pure functions
11. Pure functions Input Output No side effects Isolated from the world Transforms input -> output
12. Pure functions let eat = (food) => { let foodList = [, , , ] if(foodList.includes(food)) { return } else { return } }
13. Pure functions eat() // => eat() // =>
14. Easy to test describe("eat", () => { it("returns when ", () => { expect(eat()).toBe() }) })
15. Impure functions let eat = (food) => { let foodList = [, , , ] if(foodList.includes(food)) { console.log() } else { console.log() } } Not testable, depends on the world
16. Immutability Never change a value, create a new one
17. Immutability Functions are black boxes, changing their input is unpredictable
18. Immutability Image: joy of clojure
19. Immutability Concurrency is easy
20. Consistency
21. Class Object Instance Inheritance Polymorphism Abstract Factory Builder Factory Method Object Pool Prototype Singleton Adapter Bridge Composite Decorator Facade Flyweight Private Class Data Proxy Chain of responsibility Command Interpreter Iterator Mediator Memento Null Object Observer State
24. Immutability ❌ First class functions ✅ Consistency ❌
25. First class functions ✅ let temperatures = [10, 20, 30] let celsius2fahrenheit = (t) => t * 1.8 + 32 temperatures.map(celsius2fahrenheit) // => [ 50, 68, 86 ]
26. First class functions ✅ let temperatures = [10, 20, 30] let celsius2fahrenheit = (t) => t * 1.8 + 32 temperatures.map(celsius2fahrenheit) // => [ 50, 68, 86 ]
27. First class functions ✅ let temperatures = [10, 20, 30] let celsius2fahrenheit = (t) => t * 1.8 + 32 temperatures.map(celsius2fahrenheit) // => [ 50, 68, 86 ]
28. First class functions ✅ let temperatures = [10, 20, 30] let celsius2fahrenheit = (t) => t * 1.8 + 32 temperatures.map(celsius2fahrenheit) // => [ 50, 68, 86 ]
29. Immutability ❌ let account = {id: "acc-1", status: "active"} let account2blocked = (acc) => { acc.status = "blocked" return acc } account2blocked(account) // => {id: "acc-1", status: "blocked"} account // => {id: "acc-1", status: "blocked"}
30. Immutability ❌ let account = {id: "acc-1", status: "active"} let account2blocked = (acc) => { acc.status = "blocked" return acc } account2blocked(account) // => {id: "acc-1", status: "blocked"} account // => {id: "acc-1", status: "blocked"}
31. Immutability ❌ let account = {id: "acc-1", status: "active"} let account2blocked = (acc) => { acc.status = "blocked" return acc } account2blocked(account) // => {id: "acc-1", status: "blocked"} account // => {id: "acc-1", status: "blocked"}
32. Immutability ❌ let account = {id: "acc-1", status: "active"} let account2blocked = (acc) => { acc.status = "blocked" return acc } account2blocked(account) // => {id: "acc-1", status: "blocked"} account // => {id: "acc-1", status: "blocked"}
33. Immutability ❌ let account = {id: "acc-1", status: "active"} let account2blocked = (acc) => { acc.status = "blocked" return acc } account2blocked(account) // => {id: "acc-1", status: "blocked"} account // => {id: "acc-1", status: "blocked"}
34. Immutability ❌ let account = {id: "acc-1", status: "active"} let account2blocked = (acc) => { acc.status = "blocked" return acc } account2blocked(account) // => {id: "acc-1", status: "blocked"} account // => {id: "acc-1", status: "blocked"}
35. Spread operator const Immutability ❌
36. Immutability ❌
37. const Immutability ❌
38. const? const foo = {bar: 1} foo = {bar: 2} // => SyntaxError: Identifier 'foo' has already been declared foo.bar = 2 foo // => {bar: 2}
39. const? const foo = {bar: 1} foo = {bar: 2} // => SyntaxError: Identifier 'foo' has already been declared foo.bar = 2 foo // => {bar: 2}
40. const? const foo = {bar: 1} foo = {bar: 2} // => SyntaxError: Identifier 'foo' has already been declared foo.bar = 2 foo // => {bar: 2}
41. Spread operator Immutability ❌
42. Immutability ❌ let account = {id: "acc-1", status: "active"} let account2blocked = (acc) => { return {...acc, status: "blocked"} } account2blocked(account) // => {id: "acc-1", status: "blocked"} account // => {id: "acc-1", status: "active"}
43. Immutability ❌ let account = {id: "acc-1", status: "active"} let account2blocked = (acc) => { return {...acc, status: "blocked"} } account2blocked(account) // => {id: "acc-1", status: "blocked"} account // => {id: "acc-1", status: "active"}
44. Immutability ❌ let account = {id: "acc-1", status: "active"} let account2blocked = (acc) => { return {...acc, status: "blocked"} } account2blocked(account) // => {id: "acc-1", status: "blocked"} account // => {id: "acc-1", status: "active"}
45. Immutability ❌ let account = {id: "acc-1", status: "active"} let account2blocked = (acc) => { return {...acc, status: "blocked"} } account2blocked(account) // => {id: "acc-1", status: "blocked"} account // => {id: "acc-1", status: "active"}
46. Immutability ❌ let account = {id: "acc-1", status: "active"} let account2blocked = (acc) => { return {...acc, status: "blocked"} } account2blocked(account) // => {id: "acc-1", status: "blocked"} account // => {id: "acc-1", status: "active"}
47. Immutability ❌ Performance ❌
48. Immutability ❓
49. Consistency ❌
50. Consistency ❌
51. Consistency ❌
52. Consistency ❌
53. Consistency ❌ null undefined absent
54. Immutability ✅ First class functions ✅ Consistency ✅
55. First class functions ✅ (def temperatures [10 20 30]) (defn celsius->fahrenheit [t] (+ 32 (* t 1.8))) (map celsius->fahrenheit temperatures) ; => [50.0 68.0 86.0]
56. First class functions ✅ (def temperatures [10 20 30]) (defn celsius->fahrenheit [t] (+ 32 (* t 1.8))) (map celsius->fahrenheit temperatures) ; => [50.0 68.0 86.0]
57. First class functions ✅ (def temperatures [10 20 30]) (defn celsius->fahrenheit [t] (+ 32 (* t 1.8))) (map celsius->fahrenheit temperatures) ; => [50.0 68.0 86.0]
58. First class functions ✅ (def temperatures [10 20 30]) (defn celsius->fahrenheit [t] (+ 32 (* t 1.8))) (map celsius->fahrenheit temperatures) ; => [50.0 68.0 86.0]
59. Immutability ✅ (def account {:id "acc-1" :status :active}) (defn account->blocked [acc] (assoc acc :status :blocked) (account->blocked account) ; => {:id "acc-1" :status :blocked} account ; => {:id "acc-1" :status :active}
60. Immutability ✅ (def account {:id "acc-1" :status :active}) (defn account->blocked [acc] (assoc acc :status :blocked) (account->blocked account) ; => {:id "acc-1" :status :blocked} account ; => {:id "acc-1" :status :active}
61. Immutability ✅ (def account {:id "acc-1" :status :active}) (defn account->blocked [acc] (assoc acc :status :blocked) (account->blocked account) ; => {:id "acc-1" :status :blocked} account ; => {:id "acc-1" :status :active}
62. Immutability ✅ (def account {:id "acc-1" :status :active}) (defn account->blocked [acc] (assoc acc :status :blocked) (account->blocked account) ; => {:id "acc-1" :status :blocked} account ; => {:id "acc-1" :status :active}
63. Immutability ✅ (def account {:id "acc-1" :status :active}) (defn account->blocked [acc] (assoc acc :status :blocked) (account->blocked account) ; => {:id "acc-1" :status :blocked} account ; => {:id "acc-1" :status :active}
64. Structural Sharing A =
65. Structural Sharing A = B =
66. Structural Sharing
67. Structural Sharing A
68. Structural Sharing B
69. Consistency ✅
70. Consistency ✅ Only nil
72. JVM Bytecode
73. JVM Bytecode Node / Browser Javascript
74. Interop Using JS inside ClojureScript
75. React
76. is a LISP
78. LISP LISt Processing
79. LISP Developed in 1959
80. LISP Multiple dialects
81. JS was based on a LISP Based on Scheme, a LISP dialect
82. LISP (10 20 30)
83. LISP No Syntax, everything is a LIST (defn celsius->fahrenheit [t] (+ 32 (* t 1.8)))
84. LISP No Syntax, everything is a LIST (defn celsius->fahrenheit [t] (+ 32 (* t 1.8)))
85. LISP No Syntax, everything is a LIST (defn celsius->fahrenheit [t] (+ 32 (* t 1.8)))
86. LISP No Syntax, everything is a LIST (defn celsius->fahrenheit [t] (+ 32 (* t 1.8)))
87. LISP Homoiconic: CODE = DATA (defn celsius->fahrenheit [t] (+ 32 (* t 1.8)))
88. Dynamic Code easy to manipulate
90. Macros Functions that generate code
91. Macros Resolved in compile time
92. Macros Unless macro
93. Macros Unless macro
94. Macros Unless macro
95. Macros Unless macro
96. Pipeline operator ⚠
97. Threading macro
98. Threading macro
99. Threading macro
100. Types
101. Types
102. Pattern matching ⚠
103. Pattern matching ⚠
105. REPL Read Eval Print Loop
107. REPL Change code on runtime
108. Consistency Predictability Safety
109. ?
111. Thanks! We're hiring! @mpivaa github.com/mpivaa instagram.com/m.pivaa https://nubank.workable.com/ https://t.me/clojurebrasil https://www.braveclojure.com