Let's talk about PureScript

Presentation at Frontend Meetup Riga, August 2016.

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
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"
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
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
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
35. does purescript survive in the real world?
36. yes.
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)
54. go check it out hack cool things
55. • purescript.org • karlis.me
56. thanks