Monads Explained for OOP Developers
- 1. Monads Explained for OOP Developers NextBuild Eindhoven | September 29 | 2018 Mikhail Shilkov
- 4. “ “ Douglas Crockford, who found Good Partsin Javascript Monads are cursed — once you understand monads for yourself you lose the ability to explain them to others
- 5. “ “ Tomas Petricek, The Alan Turing Institute http://tomasp.net/academic/pa pers/monads/monads- programming.pdf Learning monads and writing a monad tutorial has also become an important milestone in learning about theory of functional programming
- 8. // Type annotation func: TypeA -> TypeB // Static methods static class Mapper { static ClassB func(ClassA a) { ... } } // Instance methods class ClassA { ClassB func() { ... } }
- 9. class Speaker { Talk nextTalk() { ... } } class Talk { Conference getConference() { ... } } class Conference { City getCity() { ... } }
- 10. static City nextTalkCity(Speaker speaker) { Talk talk = speaker.nextTalk(); Conference conf = talk.getConference(); City city = conf.getCity(); return city; }
- 13. NULL
- 14. class Speaker { Talk nextTalk() { ... } } class Talk { Conference getConference() { ... } } class Conference { City getCity() { ... } }
- 15. Speaker Nullable<Talk> nextTalk Talk Nullable<Conference> getConference Conference Nullable<City> getCity
- 16. Nullable<City> nextTalkCity Speaker Talk? nextTalk Conference? getConference City? getCity
- 17. Nullable<City> nextTalkCity Speaker Talk? nextTalk Conference? getConference City? getCity
- 19. Speaker Optional<Talk> nextTalk Talk Optional<Conference> getConference Conference Optional<City> getCity
- 23. Speaker List<Talk> getTalks Talk List<Conference> getConferences Conference List<City> getCities
- 24. List<City> allCitiesToVisit Speaker List<City> Talk getTalks Conference getConferences City getCities
- 35. PATTERN
- 36. nextTalk getConference getCity // Optional<T> getTalks getConferences getCities // List<T> nextTalk getConference getCity // CompletableFuture<T>
- 39. Monad<T> Monad<U> bind T Monad<U> // or alternatively Monad<T> Monad<U> apply T U Monad<U> unwrap Monad<Monad<U>>
- 40. Optional<T> // ... constructors go here Optional<U> flatMap T Optional<U> func func Optional
- 42. CompletableFuture CompletableFuture<U> thenCompose T CompletableFuture<U>> func // Some black magic happens here, // but it works!!!
- 43. WORKFLOW
- 45. async talk await await talk await talk
- 46. MONADS
- 47. nextTalkCity async let! nextTalk let! getConference let! getCity
- 48. nextTalkCity option let! nextTalk let! getConference let! getCity
- 51. MONAD
- 52. • Pattern • Generic Container • Workflow Builder
- 53. “ “ John De Goes, who knows what Monads are Monads are virtual machines for expressing sequential, dependent computation, where the instruction set of a VM is given by the structure of the monad's constructors