[reactive] Is Reactive.integral broken?

13 Jan 2009

      The problematic expression is:

let ticks = R.atTimes [0,0.1..] :: R.Event ()
    integration = ticks `R.integral` R.time
in integration

The value inside integration is always 0.

But here is a full sample program to demonstrate the problem:

{-# OPTIONS -fglasgow-exts -O2 -Wall #-}

import Control.Applicative
import qualified FRP.Reactive as R
import qualified Graphics.FieldTrip as FT
import Graphics.FieldTrip((*%))
import qualified FRP.Reactive.FieldTrip.Adapter as FieldTripA

resize :: (FT.Transform (FT.Transform3 s) a) => s -> a -> a
resize size = (FT.uscale3 size *%)

utext :: String -> FT.Geometry3
utext = FT.flatG . FT.utext

main :: IO ()
main = do
  let ticks = R.atTimes [0,0.1..] :: R.Event ()
      integration = ticks `R.integral` R.time
  FieldTripA.anim3 . pure $ resize (0.3::Double) . utext . show <$>
integration

[reactive] Is Reactive.integral broken?

Eyal Lotem