Repro code for https://github.com/purescript-concur/purescript-concur-core/issues/2

DebounceTest.purs

module Main where

import Prelude

import Concur.Core (Widget)
import Concur.Core.FRP (Signal, debounce, display, dyn)
import Concur.React (HTML)
import Concur.React.DOM as D
import Concur.React.Props as P
import Data.Foldable (class Foldable, fold)
import Data.Maybe (Maybe(..))
import Data.String (trim)
import Data.String.NonEmpty (NonEmptyString, fromString, toString)

type CtrlSignal v a = a -> Signal v a

main :: Effect Unit
main = runWidgetInDom "root" mainWidget

mainWidget :: forall a. Widget HTML a
mainWidget = dyn $ do
  s <- textInput D.div' "HELLO" Nothing
  display (D.div' [D.text (show s)])

foldf :: ∀ a f m. Foldable f => Functor f => Monoid m => (a -> m) -> f a -> m
foldf f vals = fold $ f <$> vals

textInputWidget :: String -> Widget HTML String
textInputWidget txt =
  D.input [P.value txt, P.unsafeTargetValue <$> P.onChange]

textInput' :: D.El' -> String -> CtrlSignal HTML String
textInput' tag label initVal = labelSig' tag label [] $ sig initVal
  where
    sig :: String -> Signal HTML String
    sig txt = debounce 500.0 txt textInputWidget

-- | Reasonable defaults for filtering input text
textFilter :: Signal HTML String -> Signal HTML (Maybe NonEmptyString)
textFilter txtSig = do
  txt <- txtSig
  pure $ fromString $ trim txt

textInput :: D.El' -> String -> CtrlSignal HTML (Maybe NonEmptyString)
textInput tag label iVal = textFilter $ textInput' tag label
  (foldf toString iVal)

-- | Prepend a label heading to a siginal
labelSig' :: ∀ a. D.El'
  -> String
  -> Array (P.ReactProps a)
  -> Signal HTML a
  -> Signal HTML a
labelSig' tag label props sigIn = labelSig (tag [D.text label]) props sigIn

labelSig :: ∀ a. (∀ b. Widget HTML b)
  -> Array (P.ReactProps a)
  -> Signal HTML a
  -> Signal HTML a
labelSig widg props sigIn = D.div_ props do
  display widg
  sigIn