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February 29, 2020 11:38
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Patterns for building fine-grained reactive datatypes
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data Triple f a b c | |
= Triple1 (f a) (f b) (f c) | |
| Triple2 (f a) (f b) (f c) | |
data TripleAction a b c where | |
Triple1Fst :: (a -> a) -> TripleAction a b c | |
Triple1Snd :: (b -> b) -> TripleAction a b c | |
Triple1Thd :: (c -> c) -> TripleAction a b c | |
Triple2Fst :: (a -> a) -> TripleAction a b c | |
Triple2Snd :: (b -> b) -> TripleAction a b c | |
Triple2Thd :: (c -> c) -> TripleAction a b c | |
TripleReplace :: Triple Identity a b c -> TripleAction a b c | |
mkTriple :: | |
(Reflex t, MonadHold t m, Adjustable t m, MonadFix m) => | |
Triple Identity a b c -> | |
Event t (TripleAction a b c) -> | |
m (Dynamic t (Triple (Dynamic t) a b c)) | |
mkTriple z e = | |
networkHold (mkNode z) $ | |
fmapMaybe | |
(\case | |
TripleReplace z' -> Just $ mkNode z' | |
_ -> Nothing) | |
e | |
where | |
mkNode n = | |
case n of | |
Triple1 (Identity a) (Identity b) (Identity c) -> | |
Triple1 <$> | |
foldDyn ($) a (fmapMaybe (\case; Triple1Fst f -> Just f; _ -> Nothing) e) <*> | |
foldDyn ($) b (fmapMaybe (\case; Triple1Snd f -> Just f; _ -> Nothing) e) <*> | |
foldDyn ($) c (fmapMaybe (\case; Triple1Thd f -> Just f; _ -> Nothing) e) | |
Triple2 (Identity a) (Identity b) (Identity c) -> | |
Triple2 <$> | |
foldDyn ($) a (fmapMaybe (\case; Triple2Fst f -> Just f; _ -> Nothing) e) <*> | |
foldDyn ($) b (fmapMaybe (\case; Triple2Snd f -> Just f; _ -> Nothing) e) <*> | |
foldDyn ($) c (fmapMaybe (\case; Triple2Thd f -> Just f; _ -> Nothing) e) | |
data List f a | |
= Nil | |
| Cons (f a) (f (List f a)) | |
data ListAction a where | |
ListCons1 :: (a -> a) -> ListAction a | |
ListCons2 :: ListAction a -> ListAction a | |
ListReplace :: (List Identity a -> List Identity a) -> ListAction a | |
data Edit a | |
= ModifyAt Int (a -> a) | |
| InsertAt Int a | |
| DeleteAt Int | |
runEdit :: Edit a -> ListAction a | |
runEdit (ModifyAt 0 f) = ListCons1 f | |
runEdit (ModifyAt n f) = ListCons2 $ runEdit (ModifyAt (n-1) f) | |
runEdit (DeleteAt 0) = | |
ListReplace (\case; Nil -> Nil; Cons _ (Identity a) -> a) | |
runEdit (DeleteAt n) = ListCons2 $ runEdit (DeleteAt (n-1)) | |
runEdit (InsertAt 0 a) = ListReplace (Cons (Identity a) . Identity) | |
runEdit (InsertAt n a) = ListCons2 $ runEdit (InsertAt (n-1) a) | |
freeze :: Monad f => List f a -> f (List Identity a) | |
freeze Nil = pure Nil | |
freeze (Cons a b) = | |
(\a' b' -> Cons (Identity a') (Identity b')) <$> a <*> (freeze =<< b) | |
mkList :: | |
(Reflex t, MonadHold t m, Adjustable t m, MonadFix m) => | |
List Identity a -> | |
Event t (ListAction a) -> | |
m (Dynamic t (List (Dynamic t) a)) | |
mkList z e = do | |
rec | |
dList <- | |
networkHold (mkNode z) $ | |
attachWithMaybe | |
(\list -> \case | |
ListReplace f -> | |
Just $ mkNode . f =<< sample (current $ freeze list) | |
_ -> Nothing) | |
(current dList) | |
e | |
pure dList | |
where | |
mkNode n = | |
case n of | |
Nil -> pure Nil | |
Cons (Identity a) (Identity b) -> | |
Cons <$> | |
foldDyn ($) a (fmapMaybe (\case; ListCons1 f -> Just f; _ -> Nothing) e) <*> | |
mkList b (fmapMaybe (\case; ListCons2 f -> Just f; _ -> Nothing) e) |
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