diff --git a/LICENSE b/LICENSE new file mode 100644 --- /dev/null +++ b/LICENSE @@ -0,0 +1,7 @@ +Copyright 2019 ATUM SOLUTIONS AG + +Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. diff --git a/reflex-external-ref.cabal b/reflex-external-ref.cabal new file mode 100644 --- /dev/null +++ b/reflex-external-ref.cabal @@ -0,0 +1,37 @@ +name: reflex-external-ref +version: 1.0.3.0 +synopsis: External reference with reactivity support +description: See README.md +stability: Experimental +category: Reflex, FRP, Web, GUI, HTML, Javascript, Reactive, Reactivity, User Interfaces, User-interface +build-type: Simple +cabal-version: >=1.10 +license: MIT +license-file: LICENSE +copyright: 2019 ATUM SOLUTIONS AG +author: + - Anton Gushcha + - Aminion + - Vladimir Krutkin + - Levon Oganyan +maintainer: - Anton Gushcha + - Aminion <> + - Vladimir Krutkin + - Levon Oganyan +bug-reports: https://github.com/hexresearch/ergvein/issues +homepage: https://github.com/hexresearch/ergvein + +library + hs-source-dirs: src + exposed-modules: + Reflex.ExternalRef + build-depends: + base >= 4.5 && < 4.15 + , reflex >= 0.4 && < 0.9 + , deepseq >= 1.4 && < 1.5 + default-language: Haskell2010 + +source-repository head + type: git + location: https://github.com/hexresearch/ergvein.git + subdir: reflex-external-ref diff --git a/src/Reflex/ExternalRef.hs b/src/Reflex/ExternalRef.hs new file mode 100644 --- /dev/null +++ b/src/Reflex/ExternalRef.hs @@ -0,0 +1,193 @@ +{-# LANGUAGE DeriveGeneric #-} +{-# LANGUAGE FlexibleContexts #-} +{-# LANGUAGE MonoLocalBinds #-} +{-# LANGUAGE RecordWildCards #-} + +-- | External reference with reactivity support. The reference is needed in glue +-- code between reflex and external libs where you cannot sample from dynamics +-- with `MonadSample`. +module Reflex.ExternalRef( + ExternalRef(..) + , newExternalRef + , readExternalRef + , writeExternalRef + , modifyExternalRef + , modifyExternalRef_ + , modifyExternalRefMaybe + , modifyExternalRefMaybe_ + , modifyExternalRefM + , modifyExternalRefM_ + , modifyExternalRefMaybeM + , modifyExternalRefMaybeM_ + , externalRefBehavior + , externalRefDynamic + , externalFromDynamic + , fmapExternalRef + ) where + +import Control.DeepSeq +import Control.Monad.IO.Class +import Data.IORef +import GHC.Generics +import Reflex + +-- | Holds value of type `a` and provides ways for notifying FRP network about +-- changes of the variable. +-- +-- This abstraction is helpful for storing counters, lists of internal resources +-- and so on. It is designed to be updated from outputs of FRP network, not from +-- outer world. +data ExternalRef t a = ExternalRef { + -- | Storage of value (do not change this by yourself, use helpers) + externalRef :: !(IORef a) + -- | Event that fires when value is changed +, externalEvent :: !(Event t a) + -- | Method of updating value of previous event +, externalFire :: !(a -> IO ()) +} deriving (Generic) + +instance NFData (ExternalRef t a) where + rnf ExternalRef{..} = + externalRef `deepseq` + externalEvent `seq` + externalFire `seq` + () + +-- | Creation of external ref in host monad +newExternalRef :: (MonadIO m, TriggerEvent t m) => a -> m (ExternalRef t a) +newExternalRef a = do + ref <- liftIO $ newIORef a + (e, fire) <- newTriggerEvent + return $ ExternalRef ref e fire + +-- | Read current value of external reference +readExternalRef :: MonadIO m => ExternalRef t a -> m a +readExternalRef ExternalRef {..} = liftIO $ readIORef externalRef + +-- | Write new value to external reference and notify FRP network. +-- The function evaluates the value to WNF. +writeExternalRef :: MonadIO m => ExternalRef t a -> a -> m () +writeExternalRef ExternalRef {..} a = do + a `seq` liftIO (writeIORef externalRef a) + _ <- liftIO $ externalFire a + return () + +-- | Atomically modify an external ref and notify FRP network. +-- The function evaluates the value to WNF. +modifyExternalRef :: MonadIO m => ExternalRef t a -> (a -> (a, b)) -> m b +modifyExternalRef ExternalRef {..} f = do + (a, b) <- liftIO $ atomicModifyIORef' externalRef $ \a -> + let (a', b) = f a in (a', (a', b)) + _ <- liftIO $ externalFire a + return b + +-- | Atomically modify an external ref and notify FRP network. +-- The function evaluates the value to WNF. Returns nothing +modifyExternalRef_ :: MonadIO m => ExternalRef t a -> (a -> a) -> m () +modifyExternalRef_ ExternalRef {..} f = do + a <- liftIO $ atomicModifyIORef' externalRef $ \a -> + let a' = f a in (a', a') + liftIO $ externalFire a + +-- | If the function evaluates to Just then +-- Atomically modify an external ref and notify FRP network. +-- The function evaluates the value to WNF. +-- Return the Maybe result of function's evaluation +modifyExternalRefMaybe :: MonadIO m => ExternalRef t a -> (a -> Maybe (a,b)) -> m (Maybe b) +modifyExternalRefMaybe ExternalRef {..} f = do + mab <- liftIO $ atomicModifyIORef' externalRef $ \a -> + maybe (a, Nothing) (\ab-> (fst ab, Just ab)) $ f a + liftIO $ maybe (pure ()) (externalFire . fst) mab + pure $ snd <$> mab + +-- | If the function evaluates to Just then +-- Atomically modify an external ref and notify FRP network. +-- The function evaluates the value to WNF. Returns nothing +-- The function discards the result +modifyExternalRefMaybe_ :: MonadIO m => ExternalRef t a -> (a -> Maybe a) -> m () +modifyExternalRefMaybe_ ExternalRef {..} f = do + ma <- liftIO $ atomicModifyIORef' externalRef $ \a -> + maybe (a, Nothing) (\a' -> (a', Just a')) $ f a + liftIO $ maybe (pure ()) externalFire ma + +-- | Modify (not atomically) an external ref and notify FRP network. +-- The function evaluates the value to WNF. +modifyExternalRefM :: MonadIO m => ExternalRef t a -> (a -> m (a, b)) -> m b +modifyExternalRefM ExternalRef {..} f = do + a <- liftIO $ readIORef externalRef + (a', b) <- f a + liftIO $ do + writeIORef externalRef a' + externalFire a' + return b + +-- | Modify (not atomically) an external ref and notify FRP network. +-- The function evaluates the value to WNF. +modifyExternalRefM_ :: MonadIO m => ExternalRef t a -> (a -> m a) -> m () +modifyExternalRefM_ ExternalRef {..} f = do + a <- liftIO $ readIORef externalRef + a' <- f a + liftIO $ do + writeIORef externalRef a' + externalFire a' + +-- | If the function evaluates to Just then +-- Modify (not atomically) an external ref and notify FRP network. +-- The function evaluates the value to WNF. +modifyExternalRefMaybeM :: MonadIO m => ExternalRef t a -> (a -> m (Maybe (a, b))) -> m (Maybe b) +modifyExternalRefMaybeM ExternalRef {..} f = do + a <- liftIO $ readIORef externalRef + mab <- f a + case mab of + Nothing -> pure Nothing + Just (a',b) -> liftIO $ do + writeIORef externalRef a' + externalFire a' + return $ Just b + +-- | If the function evaluates to Just then +-- Modify (not atomically) an external ref and notify FRP network. +-- The function evaluates the value to WNF. +-- The function discards the result +modifyExternalRefMaybeM_ :: MonadIO m => ExternalRef t a -> (a -> m (Maybe a)) -> m () +modifyExternalRefMaybeM_ ExternalRef {..} f = do + a <- liftIO $ readIORef externalRef + ma <- f a + case ma of + Nothing -> pure () + Just a' -> liftIO $ do + writeIORef externalRef a' + externalFire a' + +-- | Construct a behavior from external reference +externalRefBehavior :: (MonadHold t m, MonadIO m) => ExternalRef t a -> m (Behavior t a) +externalRefBehavior ExternalRef {..} = do + a <- liftIO $ readIORef externalRef + hold a externalEvent + +-- | Get dynamic that tracks value of the internal ref +externalRefDynamic :: (MonadHold t m, MonadIO m) => ExternalRef t a -> m (Dynamic t a) +externalRefDynamic ExternalRef {..} = do + a <- liftIO $ readIORef externalRef + holdDyn a externalEvent + +-- | Create external ref that tracks content of dynamic. Editing of the ref +-- has no effect on the original dynamic. +externalFromDynamic :: (MonadHold t m, TriggerEvent t m, PerformEvent t m, Reflex t, MonadIO m, MonadIO (Performable m)) + => Dynamic t a -> m (ExternalRef t a) +externalFromDynamic da = do + a0 <- sample . current $ da + r <- newExternalRef a0 + performEvent_ $ fmap (writeExternalRef r) $ updated da + pure r + +-- | Creates external ref as a result of "fmapping" a function to the original ref. +-- ExternalRef t is not a true Functior, since it requres monadic action to "fmap" +-- Editing of the new ref has no effect on the original dynamic. +fmapExternalRef :: (MonadIO m, TriggerEvent t m, PerformEvent t m, MonadIO (Performable m)) + => (a -> b) -> ExternalRef t a -> m (ExternalRef t b) +fmapExternalRef f ea = do + v0 <- readExternalRef ea + r <- newExternalRef $ f v0 + performEvent_ $ fmap (writeExternalRef r . f) $ externalEvent ea + pure r