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24 lines
455 B
Idris
24 lines
455 B
Idris
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||| Version of Maybe indexed by an `isJust' boolean
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module Data.IMaybe
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%default total
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public export
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data IMaybe : Bool -> Type -> Type where
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Just : a -> IMaybe True a
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Nothing : IMaybe False a
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public export
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fromJust : IMaybe True a -> a
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fromJust (Just a) = a
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public export
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Functor (IMaybe b) where
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map f (Just a) = Just (f a)
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map f Nothing = Nothing
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public export
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Applicative (IMaybe True) where
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pure = Just
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Just f <*> Just x = Just (f x)
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