41 lines
1014 B
Haskell
41 lines
1014 B
Haskell
{-# LANGUAGE TemplateHaskell #-}
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{-# LANGUAGE StrictData #-}
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{-# LANGUAGE DeriveGeneric #-}
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{-# LANGUAGE ScopedTypeVariables #-}
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module MaybeHelp where
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import Control.Lens
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import Data.Aeson
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import GHC.Generics
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import TH.Derive
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import Data.Store
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data Maybe' a = Just' {__Just' :: a} | Nothing'
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deriving (Eq,Ord,Show,Read,Generic)
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instance ToJSON a => ToJSON (Maybe' a) where
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toEncoding = genericToEncoding defaultOptions
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instance FromJSON a => FromJSON (Maybe' a)
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fromJust' :: Maybe' a -> a
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fromJust' mx = case mx of
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Just' x -> x
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Nothing' -> error "no fromJust'"
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isJust' :: Maybe' a -> Bool
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isJust' Just' {} = True
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isJust' Nothing' = False
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isNothing' :: Maybe' a -> Bool
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isNothing' Just' {} = False
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isNothing' Nothing' = True
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strictify :: Maybe a -> Maybe' a
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strictify Nothing = Nothing'
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strictify (Just x) = Just' x
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toggleJust :: Maybe a -> Maybe ()
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toggleJust Nothing = Just ()
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toggleJust _ = Nothing
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makeLenses ''Maybe'
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$($(derive [d| instance (Store a => Deriving (Store (Maybe' a))) |]))
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