{-# LANGUAGE ScopedTypeVariables #-} {-# LANGUAGE MultiParamTypeClasses #-} {-# LANGUAGE TypeFamilies #-} {-# LANGUAGE UndecidableInstances #-} {-# LANGUAGE UndecidableSuperClasses #-} ------------------------------------------------------------------------ -- | -- Module : Data.Extensible.Inclusion -- Copyright : (c) Fumiaki Kinoshita 2018 -- License : BSD3 -- -- Maintainer : Fumiaki Kinoshita <fumiexcel@gmail.com> -- ------------------------------------------------------------------------ module Data.Extensible.Inclusion ( -- * Inclusion type (⊆) , Include , inclusion , shrink , spread -- * Key-value , IncludeAssoc , Associated , Associated' , inclusionAssoc , shrinkAssoc , spreadAssoc ) where import Data.Constraint import Data.Extensible.Class import Data.Extensible.Product import Data.Extensible.Sum import Data.Extensible.Internal.Rig import Data.Proxy -- | Unicode alias for 'Include' type xs ⊆ ys = Include ys xs -- | @ys@ contains @xs@ type Include ys = Forall (Member ys) -- | Reify the inclusion of type level sets. inclusion :: forall xs ys. Include ys xs => xs :& Membership ys inclusion = hrepeatFor (Proxy :: Proxy (Member ys)) membership {-# INLINABLE inclusion #-} -- | /O(n)/ Select some elements. shrink :: (xs ⊆ ys) => ys :& h -> xs :& h shrink h = hmap (hindex h) inclusion {-# INLINE shrink #-} -- | /O(1)/ Embed to a larger union. spread :: (xs ⊆ ys) => xs :/ h -> ys :/ h spread (EmbedAt i h) = views (pieceAt i) EmbedAt inclusion h {-# INLINE spread #-} ------------------------------------------------------------------ type family Associated' (xs :: [Assoc k v]) (t :: Assoc k v) :: Constraint where Associated' xs (k ':> v) = Lookup xs k v -- | @'Associated' xs (k ':> v)@ is equivalent to @'Associate' k v xs@ class Associated' xs t => Associated xs t where getAssociation :: Membership xs t instance (Associated' xs t, t ~ (k ':> v)) => Associated xs t where getAssociation = association -- | Similar to 'Include', but this focuses on keys. type IncludeAssoc ys = Forall (Associated ys) -- | Reify the inclusion of type level sets. inclusionAssoc :: forall xs ys. IncludeAssoc ys xs => xs :& Membership ys inclusionAssoc = hrepeatFor (Proxy :: Proxy (Associated ys)) getAssociation {-# INLINABLE inclusionAssoc #-} -- | /O(n)/ Select some elements. shrinkAssoc :: (IncludeAssoc ys xs) => ys :& h -> xs :& h shrinkAssoc h = hmap (hindex h) inclusionAssoc {-# INLINE shrinkAssoc #-} -- | /O(1)/ Embed to a larger union. spreadAssoc :: (IncludeAssoc ys xs) => xs :/ h -> ys :/ h spreadAssoc (EmbedAt i h) = views (pieceAt i) EmbedAt inclusionAssoc h {-# INLINE spreadAssoc #-}