Recommandé
Contenu connexe
Similaire à FP - Scala découverte Functor/Applicative/Traverse
Similaire à FP - Scala découverte Functor/Applicative/Traverse (16)
Dernier
Dernier (15)
FP - Scala découverte Functor/Applicative/Traverse
- 1. Functor/Applicative/Traverse … pour les débutant, promis !!
- 2. Functor, Applicative, Traverse queque tu racontes ?? Wesh, tu vas me laisser tranquille avec ton Scala j’y pige rien Functor, Monad gneugneu
- 3. Sommaire ➔ Révisions sur les structures Option/Either ➔ Functor ➔ Applicative ➔ Traverse
- 4. Les révisions - Option Option[A] None Some(value)
- 5. Les révisions - Either Either[A,B] Left(error) Right(value)
- 6. Functor : Définition ‘contexte’ G catégorie A fonction f: A => B
- 7. Functor : Définition Soit un ‘contexte’ G contenant une catégorie A et une fonction f: A => B, ...
- 8. Functor : Définition … un functor possède une méthode, permettant d’appliquer la transformation f de la catégorie A vers une autre catégorie B.
- 11. Functor : In real life
- 12. Functor : In real life
- 13. Functor : In real life
- 14. Functor : In real life
- 16. Functor: Specs - Maybe Maybe[A] Nothing Just(value)
- 17. Functor: Specs - Maybe
- 18. Functor: Instance - Maybe
- 19. Functor: Instance - Maybe
- 20. Functor: Les lois - l’identité Mapper la fonction identité sur un un contexte F est équivalent au contexte lui-même.
- 21. Functor: Les lois - L’identité
- 22. Functor: Les lois - La composition Mapper une fonction f puis mapper le résultat par une fonction g équivaut à mapper une fois le résultat de la fonction f à g
- 23. Functor: Les lois - La composition
- 24. Functor: Les lois - La composition
- 25. Functor: Les lois - La composition
- 26. Functor: La composition - Introduction
- 27. Functor: La composition - Introduction
- 28. Functor: La composition - Introduction
- 29. Functor: La composition - Introduction
- 30. Functor: La composition Il est possible de mapper en une fois plusieurs functors composés entre eux avec la méthode compose.
- 38. Functor ➔ Méthode map permet d’appliquer une fonction sur une valeur contenue dans un contexte ➔ Loi identité et composition ➔ La composition des functors
- 39. Applicative - Les limites du Functor
- 40. Applicative - deux méthodes : pure
- 41. Applicative - deux méthodes : pure
- 42. Applicative - deux méthodes : ap ou <*>
- 43. Applicative - deux méthodes : ap ou <*>
- 44. Applicative - deux méthodes : ap ou <*>
- 45. Applicative - deux méthodes : ap ou <*>
- 48. Applicative: Specs - Maybe Maybe[A] Nothing Just(value)
- 49. Applicative - Instance : Maybe
- 50. Applicative - Instance : Maybe
- 51. Applicative - Instance : Maybe
- 52. Applicative - Les lois ➔ Loi identité ➔ Loi composition
- 53. Applicative - Méthodes map(n) GET api/expenses GET api/salary Service salary - expenses
- 54. Applicative - Méthodes map(n) GET api/expenses GET api/salary Service salary - expenses
- 55. Applicative - Méthodes map(n)
- 56. Applicative - Méthodes map(n)
- 57. Applicative - Méthodes map(n)
- 58. Applicative - Méthodes map(n)
- 59. Applicative - Méthodes map(n)
- 60. Applicative - Cartesian - *> & <*
- 61. Applicative - in real life 3 règles de gestion : ➔ Vérifier l’image a été uploadée ➔ Vérifier l’image est carrée ➔ Vérifier les métadatas
- 62. Applicative - in real life 3 règles de gestion : ➔ Vérifier l’image a été uploadée => 100 ms + Net ➔ Vérifier l’image est carrée => 5ms ➔ Vérifier les métadatas => 5ms
- 63. Applicative - in real life
- 64. Applicative - in real life
- 65. Applicative - in real life Right Right(imageMetadata)
- 66. Applicative - in real life Right Right(imageMetadata)
- 67. Applicative - in real life Right Right(imageMetadata)
- 68. Applicative - in real life Left(error) Right(imageMetadata)
- 69. Applicative - in real life Left(error) Left(error)
- 70. Applicative ➔ Deux méthodes ap & pure ➔ L’Applicative est un Functor ➔ Loi identité & composition
- 71. Traverse - les limites de l’applicative
- 72. Traverse - les limites de l’applicative
- 73. Traverse - les limites de l’applicative Limiter au nombre de paramètre
- 76. Traverse - Méthode sequence
- 77. Traverse - Méthode sequence
- 78. Traverse - Méthode sequence List( Right, Right, Left, Right, …, Right ) Précalculé
- 79. Traverse - une autre approche List( “Paris”, “London”, “New York”, … , “Barcelona” ) Accumulateur: Right(List())
- 80. Traverse - une autre approche List( “Paris”, “London”, “New York”, … , “Barcelona” ) getWeatherAPI Accumulateur: Right(List()) Right(parisResult)
- 81. Traverse - une autre approche List( “Paris”, “London”, “New York”, … , “Barcelona” ) getWeatherAPI Accumulateur: Right(List(parisResult)) Right(londonResult)
- 82. Traverse - une autre approche List( “Paris”, “London”, “New York”, … , “Barcelona” ) getWeatherAPI Accumulateur: Right(List(parisResult, londonResult, …, barcelonaResult)) Right(barcelonaResult)
- 83. Traverse - une autre approche List( “Paris”, “London”, “New York”, … , “Barcelona” ) getWeatherAPI Accumulateur: Right(List(parisResult)) Left
- 84. Traverse - une autre approche List( “Paris”, “London”, “New York”, … , “Barcelona” ) getWeatherAPI Accumulateur: Left(errorLondon) Left
- 85. Traverse - une autre approche ➔ Initialisation accumulateur: Applicative.pure(List())
- 86. Traverse - une autre approche ➔ Initialisation accumulateur: Applicative.pure(List()) ➔ L’accumulateur est une Applicative
- 87. Traverse - une autre approche ➔ Initialisation accumulateur: Applicative.pure(List()) ➔ L’accumulateur est une Applicative ➔ Vérification résultat courant avec l’accumulateur & MAJ: accumulateur.map2(resultat) { (acc, res) => acc ++ res }
- 88. Traverse - méthode traverse
- 89. Conclusion ➔ Améliorer la visibilité du code ➔ Performance ➔ Meilleur compréhension des outils Scala ➔ Fun
- 90. Questions ?
Notes de l'éditeur
- https://carbon.now.sh/?bg=rgba(171%2C%20184%2C%20195%2C%201)&t=base16-light&wt=bw&l=text%2Fx-scala&ds=false&dsyoff=20px&dsblur=68px&wc=false&wa=true&pv=0px&ph=0px&ln=false&fm=dm&fs=18px&lh=176%25&si=false&code=def%2520getItems(weatherDeparture%253A%2520Weather%255BInfo%255D%252C%2520%250A%2520%2520%2520%2520%2520%2520%2520%2520%2520%2520%2520%2520%2520weatherTerminal%253A%2520Weather%255BInfo%255D)%253A%2520Either%255BError%252C%2520List%255BItems%255D%255D%250A%250Aval%2520weatherBarcelona%253A%2520Weather%255BInfo%255D%2520%253D%2520Sunny(Info(%2522Barcelona%2522%252C%252025.0))%250Aval%2520weatherMTP%253A%2520Weather%255BInfo%255D%2520%253D%2520Sunny(Info(%2522Montpellier%2522%252C%252020.0))%250A%250A(weatherBarcelona%252C%2520weatherMTP).map2((wB%252C%2520wM)%2520%253D%253E%2520getItems(wB%252C%2520wMTP))&es=2x&wm=false
- Nom compliqué pour des concepts relativement simple
- TODO a decomposer
- TODO a decomposer
- TODO a decomposer
- TODO a decomposer
- Just("Hello").map(_ + " world") // Just("Hello world") Nothing.map(_ + " world") // Nothing
- VIRER =
- new Functor[Maybe] = { override def map[A, B](maybeA: Maybe[A])(f: A => B) = { maybeA match { case Just(value) => Maybe(f(value)) case Nothing => Nothing } } }
- def compute(): Either[Error, List[Int]] def plus3(x: Int): Int = x + 3 val result = compute() result.map(_map(x => plus3(x)))
- def compute(): Either[Error, List[Int]] def plus3(x: Int): Int = x + 3 val result = compute() result.map(_map(x => plus3(x)))
- def compute(): Either[Error, List[Int]] def plus3(x: Int): Int = x + 3 val result = compute() result.map(_map(x => plus3(x)))
- case class DisplayItem(name: String, price: Double) def getItems: IO[Either[Error, List[Items]]] = ??? def displayItemsToClient = Functor[IO] .compose[Either[Error, ?]] .compose[List] .map(item => ItemInfo(item.name, item.price * 2.5))
- case class DisplayItem(name: String, price: Double) def getItems: IO[Either[Error, List[Items]]] = ??? def displayItemsToClient = Functor[IO] .compose[Either[Error, ?]] .compose[List] .map(item => ItemInfo(item.name, item.price * 2.5))
- case class DisplayItem(name: String, price: Double) def getItems: IO[Either[Error, List[Items]]] = ??? def displayItemsToClient = Functor[IO] .compose[Either[Error, ?]] .compose[List] .map(item => ItemInfo(item.name, item.price * 2.5))
- case class DisplayItem(name: String, price: Double) def getItems: IO[Either[Error, List[Items]]] = ??? def displayItemsToClient = Functor[IO] .compose[Either[Error, ?]] .compose[List] .map(item => ItemInfo(item.name, item.price * 2.5))
- A supprimer
- def plus3(x: Int): Int = x + 3 Right(7) <*> Right(plus3) // Right(10) Left("An error occurred") <*> Right(plus3) // Left("An error occurred")
- TODO trait Applicative[F[_]] extends Functor[F] { def pure[A](a: A): F[A] def ap[A, B](ff: F[A => B])(fa: F[A]): F[B] def map[A, B](fa: F[A])(f: A => B): F[B] }
- TODO trait Applicative[F[_]] extends Functor[F] { def pure[A](a: A): F[A] def ap[A, B](ff: F[A => B])(fa: F[A]): F[B] def map[A, B](fa: F[A])(f: A => B): F[B] }
- new Applicative[Maybe] { def pure[A](a: A): Maybe[A] = Maybe(a) def ap[A, B](maybeF: Maybe[A => B])(maybeA: A): Maybe[B] = { (maybeF, maybeA) match { case (Just(f), Just(a)) => pure(f(a)) case _ => Nothing } } }
- new Applicative[Maybe] { def pure[A](a: A): Maybe[A] = Maybe(a) def ap[A, B](maybeF: Maybe[A => B])(maybeA: A): Maybe[B] = { (maybeF, maybeA) match { case (Just(f), Just(a)) => pure(f(a)) case _ => Nothing } } }
- new Applicative[Maybe] { def pure[A](a: A): Maybe[A] = Maybe(a) def ap[A, B](maybeF: Maybe[A => B])(maybeA: A): Maybe[B] = { (maybeF, maybeA) match { case (Just(f), Just(a)) => pure(f(a)) case _ => Nothing } } }
- def getMyExpenses(credential: Credential): Either[Error, Double] def getMySalary(credential: Credential): Either[Error, Double] def process(credential: Credential): Either[Error, Double] = { val expensesEither = getMyExpenses(credential) val salaryEither = getMySalary(credential) (expensesEither, salaryEither) match { case (Right(expenses), Right(salary)) => Right(expenses + salary) case (Left(error), _) => Left(error) case (_, Left(error)) => Left(error) } }
- def getMyExpenses(credential: Credential): Either[Error, Double] def getMySalary(credential: Credential): Either[Error, Double] def process(credential: Credential): Either[Error, Double] = { val expensesEither = getMyExpenses(credential) val salaryEither = getMySalary(credential) (expensesEither, salaryEither) match { case (Right(expenses), Right(salary)) => Right(expenses + salary) case (Left(error), _) => Left(error) case (_, Left(error)) => Left(error) } }
- def getMyExpenses(credential: Credential): Either[Error, Double] def getMySalary(credential: Credential): Either[Error, Double] def process(credential: Credential): Either[Error, Double] = { val expensesEither = getMyExpenses(credential) val salaryEither = getMySalary(credential) (expensesEither, salaryEither) match { case (Right(expenses), Right(salary)) => Right(expenses + salary) case (Left(error), _) => Left(error) case (_, Left(error)) => Left(error) } }
- def getMyExpenses(credential: Credential): Either[Error, Double] def getMySalary(credential: Credential): Either[Error, Double] def process(credential: Credential): Either[Error, Double] = { val expensesEither = getMyExpenses(credential) val salaryEither = getMySalary(credential) (expensesEither, salaryEither) match { case (Right(expenses), Right(salary)) => Right(expenses + salary) case (Left(error), _) => Left(error) case (_, Left(error)) => Left(error) } }
- def getMyExpenses(credential: Credential): Either[Error, Double] def getMySalary(credential: Credential): Either[Error, Double] def process(credential: Credential): Either[Error, Double] = { val expensesEither = getMyExpenses(credential) val salaryEither = getMySalary(credential) (expensesEither, salaryEither) match { case (Right(expenses), Right(salary)) => Right(expenses + salary) case (Left(error), _) => Left(error) case (_, Left(error)) => Left(error) } }
- def getMyExpenses(credential: Credential): Either[Error, Double] def getMySalary(credential: Credential): Either[Error, Double] def getVariousIncome(credential: Credential): Either[Error, Double] def process(credential: Credential): Either[Error, Double] = { val expensesEither = getMyExpenses(credential) val salaryEither = getMySalary(credential) val otherEither = getVariousIncome(credential) Applicative[Either[Error, ?]] .map2(expensesEither, salaryEither)((expenses, salary) => salary - expenses) Applicative[Either[Error, ?]] .map3(expensesEither, salaryEither, otherEither) { (expenses, salary, other) => salary + other - expenses } ... Applicative[Either[Error, ?]] .map22(...)(_ => ...) }
- A detailler def isUploadToS3(id: ImageId): Either[Error, URI] // 100ms + NET def isSquare(size: Size): Either[Error, Size] // 5ms def validateMetadata(image: Image): Either[Error, Metadata] // 5ms def validateImageAndExtractMetadata(image: Image): Either[Error, Metadata] = { validateMetadata(image) *> isSquare(image.size) >* isUploadToS3(image.id) }
- A detailler def isUploadToS3(id: ImageId): Either[Error, URI] // 100ms + NET def isSquare(size: Size): Either[Error, Size] // 5ms def validateMetadata(image: Image): Either[Error, Metadata] // 5ms def validateImageAndExtractMetadata(image: Image): Either[Error, Metadata] = { validateMetadata(image) *> isSquare(image.size) >* isUploadToS3(image.id) }
- A detailler def isUploadToS3(id: ImageId): Either[Error, URI] // 100ms + NET def isSquare(size: Size): Either[Error, Size] // 5ms def validateMetadata(image: Image): Either[Error, Metadata] // 5ms def validateImageAndExtractMetadata(image: Image): Either[Error, Metadata] = { validateMetadata(image) *> isSquare(image.size) >* isUploadToS3(image.id) }
- def isUploadToS3(id: ImageId): Either[Error, URI] // 100ms + NET def isSquare(size: Size): Either[Error, Size] // 5ms def validateMetadata(image: Image): Either[Error, Metadata] // 5ms def validateImageAndExtractMetadata(image: Image): Either[Error, Metadata] = { validateMetadata(image) *> isSquare(image.size) >* isUploadToS3(image.id) }
- def isUploadToS3(id: ImageId): Either[Error, URI] // 100ms + NET def isSquare(size: Size): Either[Error, Size] // 5ms def validateMetadata(image: Image): Either[Error, Metadata] // 5ms def validateImageAndExtractMetadata(image: Image): Either[Error, Metadata] = { validateMetadata(image) *> isSquare(image.size) >* isUploadToS3(image.id) }
- def isUploadToS3(id: ImageId): Either[Error, URI] // 100ms + NET def isSquare(size: Size): Either[Error, Size] // 5ms def validateMetadata(image: Image): Either[Error, Metadata] // 5ms def validateImageAndExtractMetadata(image: Image): Either[Error, Metadata] = { validateMetadata(image) *> isSquare(image.size) >* isUploadToS3(image.id) }
- def isUploadToS3(id: ImageId): Either[Error, URI] // 100ms + NET def isSquare(size: Size): Either[Error, Size] // 5ms def validateMetadata(image: Image): Either[Error, Metadata] // 5ms def validateImageAndExtractMetadata(image: Image): Either[Error, Metadata] = { validateMetadata(image) *> isSquare(image.size) >* isUploadToS3(image.id) }
- def isUploadToS3(id: ImageId): Either[Error, URI] // 100ms + NET def isSquare(size: Size): Either[Error, Size] // 5ms def validateMetadata(image: Image): Either[Error, Metadata] // 5ms def validateImageAndExtractMetadata(image: Image): Either[Error, Metadata] = { validateMetadata(image) *> isSquare(image.size) >* isUploadToS3(image.id) }
- def isUploadToS3(id: ImageId): Either[Error, URI] // 100ms + NET def isSquare(size: Size): Either[Error, Size] // 5ms def validateMetadata(image: Image): Either[Error, Metadata] // 5ms def validateImageAndExtractMetadata(image: Image): Either[Error, Metadata] = { validateMetadata(image) *> isSquare(image.size) >* isUploadToS3(image.id) }
- Detailler calculs independants
- def getWeatherAPI(city: String): Either[Error, Weather] def getWeather(cityA: String, cityB: String): Either[Error, (Weather, Weather)] = Applicative[Either[Error, ?]].tuple2(cityA, cityB)
- def getWeatherAPI(city: String): Either[Error, Weather] def getWeather(cityA: String, cityB: String, cityC: String): Either[Error, (Weather, Weather, Weather)] = Applicative[Either[Error, ?]].tuple2(cityA, cityB, cityC)
- def getWeatherAPI(city: String): Either[Error, Weather] def getWeather(cityA: String, cityB: String, cityC: String): Either[Error, (Weather, Weather, Weather)] = Applicative[Either[Error, ?]].tuple2(cityA, cityB, cityC)
- FAUX def getWeatherAPI(city: String): Either[Error, Weather] def getWeather(cities: String*): Either[Error, Seq[Weather]] = { cities.map(city => getWeatherAPI(city)) // List[Either[Error, Seq[Weather]]] }
- def getWeatherAPI(city: String): Either[Error, Weather] def getWeather(cityA: String, cityB: String, cityC: String): Either[Error, (Weather, Weather, Weather)] = Applicative[Either[Error, ?]].tuple2(cityA, cityB, cityC)
- List(Some(1), Some(2), Some(3)).sequence // Option(List(1, 2, 3)) List(Some(1), None, Some(3)).sequence // None List(Right("Felix"), Right("Jean"), Right("Rex")).sequence // Right(List("Felix", "Jean", "Rex")) List(Left, Right("Jean"), Right("Rex")).sequence // Left
- def getWeatherAPI(city: String): Either[Error, Weather] def getWeather(cities: String*): Either[Error, Seq[Weather]] = { cities.map(city => getWeatherAPI(city)).toList.sequence }
- def getWeatherAPI(city: String): Either[Error, Weather] def getWeather(cities: String*): Either[Error, Seq[Weather]] = { cities.map(city => getWeatherAPI(city)).toList.sequence }
- def getWeatherAPI(city: String): Either[Error, Weather] def getWeather(cities: String*): Either[Error, Seq[Weather]] = { cities.map(city => getWeatherAPI(city)).toList.sequence }
- def getWeatherAPI(city: String): Either[Error, Weather] def getWeather(cities: String*): Either[Error, Seq[Weather]] = { cities.map(city => getWeatherAPI(city)).toList.sequence }
- def getWeatherAPI(city: String): Either[Error, Weather] def getWeather(cities: String*): Either[Error, Seq[Weather]] = { cities.map(city => getWeatherAPI(city)).toList.sequence }
- def getWeatherAPI(city: String): Either[Error, Weather] def getWeather(cities: String*): Either[Error, Seq[Weather]] = { cities.map(city => getWeatherAPI(city)).toList.sequence }
- def getWeatherAPI(city: String): Either[Error, Weather] def getWeather(cities: String*): Either[Error, Seq[Weather]] = { cities.map(city => getWeatherAPI(city)).toList.sequence }
- def getWeatherAPI(city: String): Either[Error, Weather] def getWeather(cities: String*): Either[Error, Seq[Weather]] = { cities.map(city => getWeatherAPI(city)).toList.sequence }
- def getWeatherAPI(city: String): Either[Error, Weather] def getWeather(cities: String*): Either[Error, Seq[Weather]] = { cities.toList.traverse[Either[Error, ?], String, Weather] { city => getWeatherAPI(city) } }