The document discusses functional programming concepts in Swift such as functors, monads, and higher-order functions. It provides examples of how to use functions like map, flatMap, filter and reduce to transform collections. It also discusses topics like cognitive complexity, pure functions, and how functors are containers that can be mapped while monads support flatMapping to flatten nested collections.

2. ,
.
.

4. - https://open.kakao.com/o/
gMvUe8Kb
- https://github.com/wanbok/
LetSwiftWorkShop

5. 1.
2. /
1. filter, reduce, map, flatMap
2. iOS Swift
3. Git, Github
3.

7. (Cognitive Complexity)
SonarQube

8. .
1. .
2. (
) 1 .
3. .

9. 4 .
A. (Nesting) -
B. (Structural) - +
C. Fundamental -
D. Hybrid -

14. (Cyclomatic Complexity)
• Callback hell
• If else
SonarQube ,

15. 0. Tutorial

17. •
•
•
•
• (Side effect)
•

19. • (Pure function)
• input output,
• (Anonymous function)
• Swift Closure, Obj-c Block
• (Higher-order function)
• forEach, filter, first/last(where:), reduce
• map, flatMap, compactMap

21. For-in loop
• loop
["This", "is", “Sparta!"]
.forEach { print($0) }
// This
// is
// Sparta!

22. (Element)
["This", "is", “Sparta!"]
.filter { $0.contains("is") }
.forEach { print($0) }
// This
// is

23. ["This", "is", "Sparta!"]
.first(where: { $0.contains("is") })?
.forEach { print($0) }
// This

24. ["This", "is", "Sparta!"]
.reduce("", { (sentence, word) -> String in
sentence + " " + word
})
// "This is Sparta!"

25. , Type
(Transform)
["This", "is", "Sparta!"]
.map { (text) -> Int in return text.count }
// .map { $0.count }
// [4, 2, 7]

26. Dictionary (key, value) tuple
.
.
let result: [String] = dict
.map { (each: (key: String, value: Int)) -> String in
"(each.key): (each.value)"
}

27. map
let priceString = "100 "
let parsedNumber: Int? = Int(priceString)
parsedNumber.map { “($0 / 10) ” }
// Optional(“10 ")

28. Context
(Container)
Collection, Optional, Result , value
Value
(Content)
, context
Transform
(Function)
value value

29. (Value) Context , map function
* .

30. context
• map + flatten
[[1, 2, 3], [4, 5, 6], []]
.flatMap { (numberList) -> [Int] in
return numberList.map { $0 * $0 }
}
// [1, 4, 9, 16, 25, 36]

31. context
• (Transfrom)
let number: Int? = 10
number
.flatMap { (number) -> String? in
guard number % 2 == 0 else { return nil }
return “(number) ”
}
// Optional.some Optional.none

32. (Value) Context , flatMap
function
* .

33. Collection nil
["This", nil, "is", "Sparta!", nil]
.compactMap { $0 }
// ["This", "is", "Sparta!"]

34. flatMap
• context
• [String?].flatMap { element -> String? }
• flatMap { element -> [String?] }

35. 1.

36. ,

37. • .
• .
• .
• .
•

38. • .
• .
• .
• .
• (Nested)
• Non-local

39. class Model {
init(dictionary: [String: Any]) {
…
}
}
let dictionary: [String: Any]? = …
if let dictionary = dictionary {
let model = Model(dictionary: dictionary)
}

40. class Model {
init(dictionary: [String: Any]) {
…
}
}
let dictionary: [String: Any]? = …
dictionary.map { Model(dictionary: $0) }

41. class Model {
init(dictionary: [String: Any]) {
…
}
}
let dictionary: [String: Any]? = …
dictionary.map({ Model(dictionary: $0) })

42. class Model {
init(dictionary: [String: Any]) {
…
}
}
let dictionary: [String: Any]? = …
dictionary.map(Model.init)

43. Observable.just(())
.observeOn(MainScheduler.instance)
.flatMap(rx.closeAnimation)
.bind(to: rx.removeFromSuperview)
.disposed(by: disposeBag)

44. var contraints: ((ConstraintMaker) -> Void) {
switch self {
case .top:
return {
$0.width.equalTo(size.width)
$0.height.equalTo(size.height).priority(.high)
$0.height.lessThanOrEqualTo(self.maxHeight)
$0.top.left.right.equalToSuperview()
}
case .middle:
return {
$0.height.equalTo(size.height).priority(.high)
$0.height.lessThanOrEqualTo(maxHeight)
$0.top.equalToSuperview().inset(topOffset)
$0.left.right.equalToSuperview().inset(margins)
}
}
}
…
view.snp.makeConstraints(type.contraints)

45. class ViewController: UIViewController {
struct Dependency {
let pushDetailView: (ViewController) -> Void
let presentLoginView: (ViewController) -> Void
}
let dependency: Dependency
init(dependency: Dependency) {
self.dependency = dependency
}
func tapDetailViewButton() {
self.dependency.pushDetailView(self)
}
}

46. let dependency: ViewController.Dependency = .init(
pushDetailView: { (viewController) in
viewController
.navigationController?
.pushViewController(viewController, animated: true)
},
presentLoginView: { (viewController) in … }
)
let viewController = ViewController(dependency: dependency)

47. Functor Monad

48. Container ( Context / Wrapper)
• Array, Dictionary, Result, Optional
Functor map
Monad flatMap

49. 2. , Functor, Monad

50. • Cognitive Complexity
• https://www.sonarsource.com/resources/white-papers/cognitive-complexity.html
•
• https://ko.wikipedia.org/wiki/
%ED%95%A8%EC%88%98%ED%98%95_%ED%94%84%EB%A1%9C%EA%B7%B8
%EB%9E%98%EB%B0%8D
• Swift Functional Programming by (Naver)
•
• https://ko.wikipedia.org/wiki/%EC%9D%BC%EA%B8%89_%EA%B0%9D%EC%B2%B4
• Functors are containers
• https://bartoszmilewski.com/2014/01/14/functors-are-containers/