{-# LANGUAGE Arrows #-}
{-# LANGUAGE DeriveTraversable #-}
{-# LANGUAGE RecordWildCards #-}

{- |
Module      : LiveCoding.Migrate.NoMigration
Description : Mechanism to save state in a Cell without requiring a Data instance.

If a data type is wrapped in 'NoMigration' then it can be used as the state of a 'Cell'
without requiring it to have a 'Data' instance. The consequence is that if the type has changed
in between a livereload, then the previous saved value will be discarded, and no migration attempt
will happen.

'LiveCoding' does not export 'delay' and 'changes' from this module. These functions should be
used with a qualified import.
-}
module LiveCoding.Migrate.NoMigration where

-- base

import Control.Arrow (Arrow (arr, second), returnA, (>>>))
import Control.Monad (guard)
import Data.Data (
  Constr,
  Data (dataTypeOf, gunfold, toConstr),
  DataType,
  Fixity (Prefix),
  Typeable,
  mkConstr,
  mkDataType,
 )

-- essence-of-live-coding
import LiveCoding.Cell
import qualified LiveCoding.Cell.Feedback as Feedback
import LiveCoding.Cell.Monad (hoistCellKleisli)

-- * 'NoMigration' data type and 'Data' instance.

{- | Isomorphic to @'Maybe' a@ but has a different 'Data' instance. The 'Data' instance for @'NoMigration' a@ doesn't require a 'Data' instance for @a@.

 If a data type is wrapped in 'NoMigration' then it can be used as the state of a 'Cell'
 without requiring it to have a 'Data' instance. The consequence is that if the type has changed
 in between a livereload, then the previous saved value will be discarded, and no migration attempt
 will happen.
-}
data NoMigration a = Initialized a | Uninitialized
  deriving (Int -> NoMigration a -> ShowS
forall a. Show a => Int -> NoMigration a -> ShowS
forall a. Show a => [NoMigration a] -> ShowS
forall a. Show a => NoMigration a -> String
forall a.
(Int -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
showList :: [NoMigration a] -> ShowS
$cshowList :: forall a. Show a => [NoMigration a] -> ShowS
show :: NoMigration a -> String
$cshow :: forall a. Show a => NoMigration a -> String
showsPrec :: Int -> NoMigration a -> ShowS
$cshowsPrec :: forall a. Show a => Int -> NoMigration a -> ShowS
Show, NoMigration a -> NoMigration a -> Bool
forall a. Eq a => NoMigration a -> NoMigration a -> Bool
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: NoMigration a -> NoMigration a -> Bool
$c/= :: forall a. Eq a => NoMigration a -> NoMigration a -> Bool
== :: NoMigration a -> NoMigration a -> Bool
$c== :: forall a. Eq a => NoMigration a -> NoMigration a -> Bool
Eq, forall a b. a -> NoMigration b -> NoMigration a
forall a b. (a -> b) -> NoMigration a -> NoMigration b
forall (f :: * -> *).
(forall a b. (a -> b) -> f a -> f b)
-> (forall a b. a -> f b -> f a) -> Functor f
<$ :: forall a b. a -> NoMigration b -> NoMigration a
$c<$ :: forall a b. a -> NoMigration b -> NoMigration a
fmap :: forall a b. (a -> b) -> NoMigration a -> NoMigration b
$cfmap :: forall a b. (a -> b) -> NoMigration a -> NoMigration b
Functor, forall a. Eq a => a -> NoMigration a -> Bool
forall a. Num a => NoMigration a -> a
forall a. Ord a => NoMigration a -> a
forall m. Monoid m => NoMigration m -> m
forall a. NoMigration a -> Bool
forall a. NoMigration a -> Int
forall a. NoMigration a -> [a]
forall a. (a -> a -> a) -> NoMigration a -> a
forall m a. Monoid m => (a -> m) -> NoMigration a -> m
forall b a. (b -> a -> b) -> b -> NoMigration a -> b
forall a b. (a -> b -> b) -> b -> NoMigration a -> b
forall (t :: * -> *).
(forall m. Monoid m => t m -> m)
-> (forall m a. Monoid m => (a -> m) -> t a -> m)
-> (forall m a. Monoid m => (a -> m) -> t a -> m)
-> (forall a b. (a -> b -> b) -> b -> t a -> b)
-> (forall a b. (a -> b -> b) -> b -> t a -> b)
-> (forall b a. (b -> a -> b) -> b -> t a -> b)
-> (forall b a. (b -> a -> b) -> b -> t a -> b)
-> (forall a. (a -> a -> a) -> t a -> a)
-> (forall a. (a -> a -> a) -> t a -> a)
-> (forall a. t a -> [a])
-> (forall a. t a -> Bool)
-> (forall a. t a -> Int)
-> (forall a. Eq a => a -> t a -> Bool)
-> (forall a. Ord a => t a -> a)
-> (forall a. Ord a => t a -> a)
-> (forall a. Num a => t a -> a)
-> (forall a. Num a => t a -> a)
-> Foldable t
product :: forall a. Num a => NoMigration a -> a
$cproduct :: forall a. Num a => NoMigration a -> a
sum :: forall a. Num a => NoMigration a -> a
$csum :: forall a. Num a => NoMigration a -> a
minimum :: forall a. Ord a => NoMigration a -> a
$cminimum :: forall a. Ord a => NoMigration a -> a
maximum :: forall a. Ord a => NoMigration a -> a
$cmaximum :: forall a. Ord a => NoMigration a -> a
elem :: forall a. Eq a => a -> NoMigration a -> Bool
$celem :: forall a. Eq a => a -> NoMigration a -> Bool
length :: forall a. NoMigration a -> Int
$clength :: forall a. NoMigration a -> Int
null :: forall a. NoMigration a -> Bool
$cnull :: forall a. NoMigration a -> Bool
toList :: forall a. NoMigration a -> [a]
$ctoList :: forall a. NoMigration a -> [a]
foldl1 :: forall a. (a -> a -> a) -> NoMigration a -> a
$cfoldl1 :: forall a. (a -> a -> a) -> NoMigration a -> a
foldr1 :: forall a. (a -> a -> a) -> NoMigration a -> a
$cfoldr1 :: forall a. (a -> a -> a) -> NoMigration a -> a
foldl' :: forall b a. (b -> a -> b) -> b -> NoMigration a -> b
$cfoldl' :: forall b a. (b -> a -> b) -> b -> NoMigration a -> b
foldl :: forall b a. (b -> a -> b) -> b -> NoMigration a -> b
$cfoldl :: forall b a. (b -> a -> b) -> b -> NoMigration a -> b
foldr' :: forall a b. (a -> b -> b) -> b -> NoMigration a -> b
$cfoldr' :: forall a b. (a -> b -> b) -> b -> NoMigration a -> b
foldr :: forall a b. (a -> b -> b) -> b -> NoMigration a -> b
$cfoldr :: forall a b. (a -> b -> b) -> b -> NoMigration a -> b
foldMap' :: forall m a. Monoid m => (a -> m) -> NoMigration a -> m
$cfoldMap' :: forall m a. Monoid m => (a -> m) -> NoMigration a -> m
foldMap :: forall m a. Monoid m => (a -> m) -> NoMigration a -> m
$cfoldMap :: forall m a. Monoid m => (a -> m) -> NoMigration a -> m
fold :: forall m. Monoid m => NoMigration m -> m
$cfold :: forall m. Monoid m => NoMigration m -> m
Foldable, Functor NoMigration
Foldable NoMigration
forall (t :: * -> *).
Functor t
-> Foldable t
-> (forall (f :: * -> *) a b.
    Applicative f =>
    (a -> f b) -> t a -> f (t b))
-> (forall (f :: * -> *) a. Applicative f => t (f a) -> f (t a))
-> (forall (m :: * -> *) a b.
    Monad m =>
    (a -> m b) -> t a -> m (t b))
-> (forall (m :: * -> *) a. Monad m => t (m a) -> m (t a))
-> Traversable t
forall (m :: * -> *) a.
Monad m =>
NoMigration (m a) -> m (NoMigration a)
forall (f :: * -> *) a.
Applicative f =>
NoMigration (f a) -> f (NoMigration a)
forall (m :: * -> *) a b.
Monad m =>
(a -> m b) -> NoMigration a -> m (NoMigration b)
forall (f :: * -> *) a b.
Applicative f =>
(a -> f b) -> NoMigration a -> f (NoMigration b)
sequence :: forall (m :: * -> *) a.
Monad m =>
NoMigration (m a) -> m (NoMigration a)
$csequence :: forall (m :: * -> *) a.
Monad m =>
NoMigration (m a) -> m (NoMigration a)
mapM :: forall (m :: * -> *) a b.
Monad m =>
(a -> m b) -> NoMigration a -> m (NoMigration b)
$cmapM :: forall (m :: * -> *) a b.
Monad m =>
(a -> m b) -> NoMigration a -> m (NoMigration b)
sequenceA :: forall (f :: * -> *) a.
Applicative f =>
NoMigration (f a) -> f (NoMigration a)
$csequenceA :: forall (f :: * -> *) a.
Applicative f =>
NoMigration (f a) -> f (NoMigration a)
traverse :: forall (f :: * -> *) a b.
Applicative f =>
(a -> f b) -> NoMigration a -> f (NoMigration b)
$ctraverse :: forall (f :: * -> *) a b.
Applicative f =>
(a -> f b) -> NoMigration a -> f (NoMigration b)
Traversable)

fromNoMigration :: a -> NoMigration a -> a
fromNoMigration :: forall a. a -> NoMigration a -> a
fromNoMigration a
_ (Initialized a
a) = a
a
fromNoMigration a
a NoMigration a
Uninitialized = a
a

dataTypeNoMigration :: DataType
dataTypeNoMigration :: DataType
dataTypeNoMigration = String -> [Constr] -> DataType
mkDataType String
"NoMigration" [Constr
initializedConstr, Constr
uninitializedConstr]

initializedConstr :: Constr
initializedConstr :: Constr
initializedConstr = DataType -> String -> [String] -> Fixity -> Constr
mkConstr DataType
dataTypeNoMigration String
"Initialized" [] Fixity
Prefix

uninitializedConstr :: Constr
uninitializedConstr :: Constr
uninitializedConstr = DataType -> String -> [String] -> Fixity -> Constr
mkConstr DataType
dataTypeNoMigration String
"Uninitialized" [] Fixity
Prefix

-- |The Data instance for @'NoMigration' a@ doesn't require a 'Data' instance for @a@.
instance (Typeable a) => Data (NoMigration a) where
  dataTypeOf :: NoMigration a -> DataType
dataTypeOf NoMigration a
_ = DataType
dataTypeNoMigration
  toConstr :: NoMigration a -> Constr
toConstr (Initialized a
_) = Constr
initializedConstr
  toConstr NoMigration a
Uninitialized = Constr
uninitializedConstr
  gunfold :: forall (c :: * -> *).
(forall b r. Data b => c (b -> r) -> c r)
-> (forall r. r -> c r) -> Constr -> c (NoMigration a)
gunfold forall b r. Data b => c (b -> r) -> c r
_cons forall r. r -> c r
nil Constr
_ = forall r. r -> c r
nil forall a. NoMigration a
Uninitialized

-- * Utility functions which internally use 'NoMigration'.

{- | Like 'Feedback.delay', but doesn't require 'Data' instance, and only migrates the
 last value if it still has the same type.
-}
delay :: (Monad m, Typeable a) => a -> Cell m a a
delay :: forall (m :: * -> *) a. (Monad m, Typeable a) => a -> Cell m a a
delay a
a = forall (a :: * -> * -> *) b c. Arrow a => (b -> c) -> a b c
arr forall a. a -> NoMigration a
Initialized forall {k} (cat :: k -> k -> *) (a :: k) (b :: k) (c :: k).
Category cat =>
cat a b -> cat b c -> cat a c
>>> forall s (m :: * -> *). (Data s, Monad m) => s -> Cell m s s
Feedback.delay forall a. NoMigration a
Uninitialized forall {k} (cat :: k -> k -> *) (a :: k) (b :: k) (c :: k).
Category cat =>
cat a b -> cat b c -> cat a c
>>> forall (a :: * -> * -> *) b c. Arrow a => (b -> c) -> a b c
arr (forall a. a -> NoMigration a -> a
fromNoMigration a
a)

{- | Like 'Utils.changes', but doesn't require Data instance, and only migrates the last
 value if it still is of the same type.
-}
changes :: (Typeable a, Eq a, Monad m) => Cell m a (Maybe a)
changes :: forall a (m :: * -> *).
(Typeable a, Eq a, Monad m) =>
Cell m a (Maybe a)
changes = proc a
a -> do
  Maybe a
aLast <- forall (m :: * -> *) a. (Monad m, Typeable a) => a -> Cell m a a
delay forall a. Maybe a
Nothing -< forall a. a -> Maybe a
Just a
a
  forall (a :: * -> * -> *) b. Arrow a => a b b
returnA
    -< do
      a
aLast' <- Maybe a
aLast
      forall (f :: * -> *). Alternative f => Bool -> f ()
guard forall a b. (a -> b) -> a -> b
$ a
a forall a. Eq a => a -> a -> Bool
/= a
aLast'
      forall (m :: * -> *) a. Monad m => a -> m a
return a
a

{- | Caching version of 'arrM'.

   Only runs the computation in @m@ when the input value
   changes. Meanwhile it keeps outputing the last outputted value. Also runs the computation
   on the first tick. Does not require 'Data' instance. On `:livereload` will run action again on
   first tick.
-}
arrChangesM :: (Monad m, Typeable a, Typeable b, Eq a) => (a -> m b) -> Cell m a b
arrChangesM :: forall (m :: * -> *) a b.
(Monad m, Typeable a, Typeable b, Eq a) =>
(a -> m b) -> Cell m a b
arrChangesM a -> m b
f = Cell {cellState :: NoMigration (a, b)
cellState = forall a. NoMigration a
Uninitialized, NoMigration (a, b) -> a -> m (b, NoMigration (a, b))
cellStep :: NoMigration (a, b) -> a -> m (b, NoMigration (a, b))
cellStep :: NoMigration (a, b) -> a -> m (b, NoMigration (a, b))
..}
  where
    cellStep :: NoMigration (a, b) -> a -> m (b, NoMigration (a, b))
cellStep NoMigration (a, b)
Uninitialized a
a = a -> m (b, NoMigration (a, b))
h a
a
    cellStep (Initialized (a
a', b
b)) a
a =
      if a
a forall a. Eq a => a -> a -> Bool
== a
a'
        then forall (m :: * -> *) a. Monad m => a -> m a
return (b
b, forall a. a -> NoMigration a
Initialized (a
a, b
b))
        else a -> m (b, NoMigration (a, b))
h a
a
    h :: a -> m (b, NoMigration (a, b))
h a
a = (\b
b' -> (b
b', forall a. a -> NoMigration a
Initialized (a
a, b
b'))) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> a -> m b
f a
a

cellNoMigration :: (Typeable s, Functor m) => s -> (s -> a -> m (b, s)) -> Cell m a b
cellNoMigration :: forall s (m :: * -> *) a b.
(Typeable s, Functor m) =>
s -> (s -> a -> m (b, s)) -> Cell m a b
cellNoMigration s
state s -> a -> m (b, s)
step = Cell {cellState :: NoMigration s
cellState = forall a. NoMigration a
Uninitialized, NoMigration s -> a -> m (b, NoMigration s)
cellStep :: NoMigration s -> a -> m (b, NoMigration s)
cellStep :: NoMigration s -> a -> m (b, NoMigration s)
..}
  where
    cellStep :: NoMigration s -> a -> m (b, NoMigration s)
cellStep NoMigration s
Uninitialized a
a = forall (a :: * -> * -> *) b c d.
Arrow a =>
a b c -> a (d, b) (d, c)
second forall a. a -> NoMigration a
Initialized forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> s -> a -> m (b, s)
step s
state a
a
    cellStep (Initialized s
s) a
a = forall (a :: * -> * -> *) b c d.
Arrow a =>
a b c -> a (d, b) (d, c)
second forall a. a -> NoMigration a
Initialized forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> s -> a -> m (b, s)
step s
s a
a