rhine-0.5.0.0: src/FRP/Rhine/ResamplingBuffer/KeepLast.hs

{- |
A buffer keeping the last value, or zero-order hold.
-}

{-# LANGUAGE RecordWildCards #-}
module FRP.Rhine.ResamplingBuffer.KeepLast where

import FRP.Rhine.ResamplingBuffer
import FRP.Rhine.ResamplingBuffer.Timeless

-- | Always keeps the last input value,
--   or in case of no input an initialisation value.
--   If @cl2@ approximates continuity,
--   this behaves like a zero-order hold.
keepLast :: Monad m => a -> ResamplingBuffer m cl1 cl2 a a
keepLast = timelessResamplingBuffer AsyncMealy {..}
  where
    amPut _ a = return a
    amGet   a = return (a, a)