Let's talk about PureScript

Transcript

1. an exciting trip through history prelude

2. 1936 Lambda Calculus is born

3. 1990 A bunch of smart people start working Haskell

4. 1995 Brendan Eich is hired by NetScape to write Scheme

   for the browser

5. Spoiler alert: He doesn't write a Scheme for NetScape

6. 2016

7. You shouldn't be sad.

8. Maybe those functional dudes got something right.

9. let's talk about purescript Kārlis Lauva @skazhy frontend rīga meetup,

   2016

10. Hello. I write Clojure and dabble with other things This

    is not a monad tutorial This is, like, my opinion

11. So, Haskell for the browser, eh

12. module Main where import Prelude import Control.Monad.Eff import Control.Monad.Eff.Console sup

    :: String -> String sup g = "sup, " ++ g main :: forall e. Eff (console :: CONSOLE | e) Unit main = do log $ sup "world"
13. None

14. (function(exports) { "use strict"; var Prelude = PS["Prelude"]; var Control_Monad_Eff

    = PS["Control.Monad.Eff"]; var Control_Monad_Eff_Console = PS["Control.Monad.Eff.Console"]; var sup = function (g) { return "sup, " + g; }; var main = Control_Monad_Eff_Console.log(sup("world")); exports["main"] = main; exports["sup"] = sup;; })(PS["Main"] = PS["Main"] || {}); PS["Main"].main();

15. Y

16. turns out, functional programming languages are really useful for web

    things

17. but javascript too can be purely functional

18. None

19. let's discuss the bad parts

20. [Object object]

21. an *actual* type system

22. purescript makes this example boring

23. like, really boring

24. sketchy branching

25. None
26. None

27. pattern matching

28. data Behavior = KillHumans | BeNiceToHumans type Robot = {

    naughty :: Boolean } interactWithHumans :: Robot -> Behavior interactWithHumans { naughty: true } = KillHumans interactWithHumans { naughty: false } = BeNiceToHumans

29. data Behavior = KillAllHumans | BeNiceToHumans | KillOnlyVapers type Robot

    = { niceness :: Int } interactWithHumans :: Robot -> Behavior interactWithHumans { niceness: 0 } = KillAllHumans interactWithHumans { niceness: 1 } = KillOnlyVapers interactWithHumans _ = BeNiceToHumans

30. callback hell

31. monads

32. fetchRobots(function(response) { assembleFleet(function(robots) { if (robots) return robots; }, function(error

    { .. }); }, function(error) {... });

33. data RobotArmy = Army (List Robot) fetchRobots = do robotParts

    <- get "/robotParts" robots <- assembleFleet robotParts return $ Army robots
34. None

35. does purescript survive in the real world?

36. yes.

37. None

38. ecosystem and tooling

39. psc short for "purescript compiler"

40. modules managed via bower

41. • build tool => pulp • hoogle for purescript =>

    pursuit

42. purescript - javascript teamwork

43. back to killer robots

44. data Behavior = KillHumans | BeNiceToHumans instance showBehavior :: Show

    Behavior where show KillHumans = "kill all humans11" show BeNiceToHumans = "humans, you are pretty tite" type Robot = { naughty :: Boolean } interactWithHumans :: Robot -> Behavior interactWithHumans { naughty: true } = KillHumans interactWithHumans { naughty: false } = BeNiceToHumans safeInteract :: Boolean -> String safeInteract x = show $ interactWithHumans { crazyMurderer : x }

45. PS.Main.safeInteract(isCrazyMurderingRobot)();

46. but will purescript react?

47. yes.

48. ok, so what have we learned

49. so should we all switch to purescript today?

50. not _all_ of us

51. most of the internet runs on vanilla javascript just fine

    (for years)
52. None
53. None

54. go check it out hack cool things

55. • purescript.org • karlis.me

56. thanks