1 files changed, 63 insertions, 0 deletions
diff --git a/lib/Hakyll/Core/Item.hs b/lib/Hakyll/Core/Item.hs
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+++ b/lib/Hakyll/Core/Item.hs
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+--------------------------------------------------------------------------------
+-- | An item is a combination of some content and its 'Identifier'. This way, we
+-- can still use the 'Identifier' to access metadata.
+{-# LANGUAGE DeriveDataTypeable #-}
+module Hakyll.Core.Item
+    ( Item (..)
+    , itemSetBody
+    , withItemBody
+    ) where
+
+
+--------------------------------------------------------------------------------
+import           Data.Binary                   (Binary (..))
+import           Data.Foldable                 (Foldable (..))
+import           Data.Typeable                 (Typeable)
+import           Prelude                       hiding (foldr)
+
+
+--------------------------------------------------------------------------------
+import           Hakyll.Core.Compiler.Internal
+import           Hakyll.Core.Identifier
+
+
+--------------------------------------------------------------------------------
+data Item a = Item
+    { itemIdentifier :: Identifier
+    , itemBody       :: a
+    } deriving (Show, Typeable)
+
+
+--------------------------------------------------------------------------------
+instance Functor Item where
+    fmap f (Item i x) = Item i (f x)
+
+
+--------------------------------------------------------------------------------
+instance Foldable Item where
+    foldr f z (Item _ x) = f x z
+
+
+--------------------------------------------------------------------------------
+instance Traversable Item where
+    traverse f (Item i x) = Item i <$> f x
+
+
+--------------------------------------------------------------------------------
+instance Binary a => Binary (Item a) where
+    put (Item i x) = put i >> put x
+    get            = Item <$> get <*> get
+
+
+--------------------------------------------------------------------------------
+itemSetBody :: a -> Item b -> Item a
+itemSetBody x (Item i _) = Item i x
+
+
+--------------------------------------------------------------------------------
+-- | Perform a compiler action on the item body. This is the same as 'traverse',
+-- but looks less intimidating.
+--
+-- > withItemBody = traverse
+withItemBody :: (a -> Compiler b) -> Item a -> Compiler (Item b)
+withItemBody = traverse