![Similarities - Function composition
Scala
List(1,2,3) map (_ + 1) filter (_ > 3)
val plus3: Int => Int = (_ + 3)
val plus3Times4 = plus3 >>> (_ * 4)
PureScript
[1,2,3] # map (_ + 1) # filter (_ > 3)
plus3 = (_ + 3)
plus3Times4 = plus3 >>> (_ * 4)](https://image.slidesharecdn.com/curryon-170619220002/85/Reactive-Programming-in-the-Browser-feat-Scala-js-and-PureScript-5-320.jpg)
![Similarities - ADTs and Pattern Matching
Scala
sealed trait Maybe[+T]
case class Just[T](t: T) extends
Maybe[T]
case object Nada extends
Maybe[Nothing]
x match {
case Just(a) => ...
case Nada => ...
}
PureScript
data Maybe a = Just a | Nada
case x of
(Just a) -> ...
Nada -> ...](https://image.slidesharecdn.com/curryon-170619220002/85/Reactive-Programming-in-the-Browser-feat-Scala-js-and-PureScript-6-320.jpg)
![Similarities - Monadic comprehensions
Scala
for {
z <- 1 to 20
y <- 1 to z
x <- 1 to y
if x * x + y * y == z * z
} yield (x, y, z)
PureScript
do
z <- 1 .. 20
y <- 1 .. z
x <- 1 .. y
guard $ x * x + y * y == z * z
pure [x, y, z]](https://image.slidesharecdn.com/curryon-170619220002/85/Reactive-Programming-in-the-Browser-feat-Scala-js-and-PureScript-7-320.jpg)
![Similarities - Higher Kinded Types
Scala
trait Functor[F[_]] {
def map[A, B](f: A => B)
(fa: F[A]): F[B]
}
PureScript
class Functor f where
map :: forall a b. (a -> b)
-> f a
-> f b](https://image.slidesharecdn.com/curryon-170619220002/85/Reactive-Programming-in-the-Browser-feat-Scala-js-and-PureScript-8-320.jpg)
![OutWatch
Scala
val logComponent: VNode = div(
h2("Input here"),
input(inputString → loggingSink)
)
PureScript
logComponent :: forall e.
VDom (console :: CONSOLE | e)
logComponent =
div
[ h2[ text "Input here" ]
, input[inputString ⇒ loggingSink]
]](https://image.slidesharecdn.com/curryon-170619220002/85/Reactive-Programming-in-the-Browser-feat-Scala-js-and-PureScript-16-320.jpg)
Reactive Programming in the Browser feat. Scala.js and PureScript
- 1. Reactive Programming in the Browser Luka Jacobowitz
- 2. Agenda 1. Intro to Scala.js and PureScript 2. What exactly is Reactive Programming? 3. Why use Reactive Programming? 4. Live Coding session!
- 3. Scala.js ● First appeared in 2013 ● Simple Scala to JavaScript compiler ● Can compile almost Scala code without any changes to existing code
- 4. PureScript ● First appeared in 2013 ● Strongly inspired by Haskell ● Purely Functional ● Built explicitly for the Browser/JavaScript environment
- 5. Similarities - Function composition Scala List(1,2,3) map (_ + 1) filter (_ > 3) val plus3: Int => Int = (_ + 3) val plus3Times4 = plus3 >>> (_ * 4) PureScript [1,2,3] # map (_ + 1) # filter (_ > 3) plus3 = (_ + 3) plus3Times4 = plus3 >>> (_ * 4)
- 6. Similarities - ADTs and Pattern Matching Scala sealed trait Maybe[+T] case class Just[T](t: T) extends Maybe[T] case object Nada extends Maybe[Nothing] x match { case Just(a) => ... case Nada => ... } PureScript data Maybe a = Just a | Nada case x of (Just a) -> ... Nada -> ...
- 7. Similarities - Monadic comprehensions Scala for { z <- 1 to 20 y <- 1 to z x <- 1 to y if x * x + y * y == z * z } yield (x, y, z) PureScript do z <- 1 .. 20 y <- 1 .. z x <- 1 .. y guard $ x * x + y * y == z * z pure [x, y, z]
- 8. Similarities - Higher Kinded Types Scala trait Functor[F[_]] { def map[A, B](f: A => B) (fa: F[A]): F[B] } PureScript class Functor f where map :: forall a b. (a -> b) -> f a -> f b
- 9. Differences Scala ● Inheritance (can make working with JS APIs easier) ● Allows partial application of any parameter ● Needs a runtime environment ● Larger tool/library ecosystem ● Implicits ● String interpolation ● Supports Dynamic typing PureScript ● Guarantees referential transparency ● Functions are all curried by default ● JS semantics ● Eff optimizes out calls to bind ● ST compiles to JS variable ● Hindley-Milner Inference ● Nested Record Updates ● Row Polymorphism
- 10. How do we develop user interfaces with pure functional programming?
- 11. Reactive Programming Reactive programming is programming with asynchronous data streams.
- 12. How is that useful?
- 13. How is that useful?
- 14. Let’s check out some code!
- 15. OutWatch A small library with 3 design goals ● Updating DOM efficiently without sacrificing abstraction => Virtual DOM ● Handling subscriptions automatically ● Removing or restricting the need for Higher Order Observables
- 16. OutWatch Scala val logComponent: VNode = div( h2("Input here"), input(inputString → loggingSink) ) PureScript logComponent :: forall e. VDom (console :: CONSOLE | e) logComponent = div [ h2[ text "Input here" ] , input[inputString ⇒ loggingSink] ]
- 17. More code!
- 18. Thank you for listening! You can find out more at http://outwatch.github.io. Or check out my twitter @LukaJacobowitz and my Blog http://lukajcb.github.io/blog