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| {-# Language MultiParamTypeClasses, PolyKinds #-} | |
| module Monads where | |
| import Control.Monad.Reader | |
| import Data.Binary.Get | |
| import Data.Proxy | |
| import qualified Data.ByteString.Lazy as BS | |
| type ReadContext = String | |
| type MyGetM m = ReaderT ReadContext m | |
| type MyGetter t m = MyGetM m | |
| data ProtoProxy t m = ProtoProxy | |
| protofoo :: ProtoProxy ProtoFoo Get | |
| protofoo = ProtoProxy | |
| class Monad m => Proto t m where | |
| getTop :: ProtoProxy t m -> BS.ByteString -> String | |
| getBool :: MyGetter t m Bool | |
| getString :: MyGetter t m String | |
| data ProtoFoo = ProtoFoo | |
| type FooGetter = MyGetter ProtoFoo Get | |
| instance Proto ProtoFoo Get where | |
| getTop _ s = runGet (runReaderT (getString :: FooGetter String) "foo") s | |
| getString = ask | |
| getBool = do | |
| v <- lift getWord8 | |
| return (v /= 0) | |
| runMe :: Proto t m => ProtoProxy t m -> String | |
| runMe p = getTop p BS.empty |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| {-# Language MultiParamTypeClasses, PolyKinds #-} | |
| module Monads where | |
| import Control.Monad.Reader | |
| import Data.Binary.Get | |
| import Data.Proxy | |
| import qualified Data.ByteString.Lazy as BS | |
| type ReadContext = String | |
| type MyGetM m = ReaderT ReadContext m | |
| data MyGetter t m a = MyGetter (MyGetM m a) | |
| instance Functor m => Functor (MyGetter t m) where | |
| fmap f (MyGetter g) = MyGetter (fmap f g) | |
| instance Applicative m => Applicative (MyGetter t m) where | |
| pure v = MyGetter (pure v) | |
| (MyGetter a) <*> (MyGetter b) = MyGetter (a <*> b) | |
| instance Monad m => Monad (MyGetter t m) where | |
| (MyGetter a) >>= g = let unget (MyGetter a) = a | |
| in MyGetter (a >>= (unget . g)) | |
| data ProtoProxy t m = ProtoProxy | |
| protofoo :: ProtoProxy ProtoFoo Get | |
| protofoo = ProtoProxy | |
| class Monad m => Proto t m where | |
| getTop :: ProtoProxy t m -> BS.ByteString -> String | |
| getBool :: MyGetter t m Bool | |
| getString :: MyGetter t m String | |
| data ProtoFoo = ProtoFoo | |
| type FooGetter = MyGetter ProtoFoo Get | |
| instance Proto ProtoFoo Get where | |
| getTop _ s = let MyGetter g = getString :: FooGetter String | |
| in runGet (runReaderT g "foo") s | |
| getString = MyGetter ask | |
| getBool = do | |
| v <- MyGetter (lift getWord8) | |
| return (v /= 0) | |
| runMe :: Proto t m => ProtoProxy t m -> String | |
| runMe p = getTop p BS.empty |
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