Pagination Example

Main.purs

module Main where

import Prelude

import Effect (Effect)
import Effect.Aff (Aff, launchAff_)
import Effect.Class (liftEffect)
import Effect.Class.Console as Console
import Effect.Ref (Ref)
import Effect.Ref as Ref
import TryPureScript (render, withConsole)

type Response = { body :: Array String, done :: Boolean }

fakeAPI :: Int -> Aff (Aff Response)
fakeAPI pages = do
  remaining <- liftEffect (Ref.new pages)
  pure do
    remaining' <- liftEffect (Ref.read remaining)
    if remaining' < 1
      then pure { body: ["final chunk"], done: true }
      else do
        liftEffect (Ref.modify_ (_ - 1) remaining)
        pure { body: ["chunk: " <> show (pages - remaining')], done: false }


requestPages :: Aff Response -> Aff (Array String)
requestPages api = do
  result <- liftEffect (Ref.new [])
  go result
  where
    go :: Ref (Array String) -> Aff (Array String)
    go result = do
      { body, done } <- api
      liftEffect (Ref.modify_ (_ <> body) result)
      if done then liftEffect (Ref.read result) else go result

main :: Effect Unit
main = render <=< withConsole $ launchAff_ do
  api <- fakeAPI 10
  chunks <- requestPages api
  Console.logShow chunks