31 lines
799 B
Haskell
31 lines
799 B
Haskell
{-# LANGUAGE MultiParamTypeClasses #-}
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{-# LANGUAGE FlexibleContexts #-}
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{-# LANGUAGE GeneralizedNewtypeDeriving #-}
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{-# LANGUAGE DeriveGeneric #-}
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module Data (
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Key(..)
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, RW(..)
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) where
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import Data.Aeson (FromJSON(..), ToJSON(..), ToJSONKey(..), genericToEncoding)
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import Data.Aeson.Types (toJSONKeyText)
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import Data.Text (pack)
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import GHC.Generics
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import qualified JSON (defaultOptions)
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class RW a b where
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get :: b -> a
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set :: a -> b -> b
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update :: (a -> a) -> b -> b
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update f v =
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set (f (get v)) v
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newtype Key a = Key Int deriving (Eq, Ord, Enum, Read, Show, Generic)
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instance FromJSON (Key a)
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instance ToJSON (Key a) where
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toEncoding = genericToEncoding JSON.defaultOptions
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instance ToJSONKey (Key a) where
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toJSONKey = toJSONKeyText (pack . \(Key n) -> show n)
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