36 lines
732 B
Haskell
36 lines
732 B
Haskell
module Util
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( toMaybe
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, dup
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, secondClassLensNames
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, (??)
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, Never
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, never
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, note
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) where
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import Data.Bool (bool)
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import Lens.Micro.TH (LensRules, lensRules, lensField, DefName (TopName))
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import Language.Haskell.TH (mkName, nameBase)
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import Lens.Micro
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toMaybe :: Bool -> a -> Maybe a
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toMaybe p = if p then Just else const Nothing
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dup :: a -> (a, a)
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dup a = (a, a)
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infixl 4 ??
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(??) :: Functor f => f (a -> b) -> a -> f b
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f ?? a = ($ a) <$> f
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secondClassLensNames :: LensRules
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secondClassLensNames = lensRules & lensField .~ (\_ _ n -> [TopName $ mkName $ nameBase n ++ "L"])
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data Never
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never :: Never -> a
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never n = case n of
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note :: a -> Maybe b -> Either a b
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note _ (Just b) = Right b
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note n Nothing = Left n |