Merge pull request #112 from simukis/sorting

Make chronological and recentFirst to respect metadata

2 files changed, 17 insertions, 8 deletions

diff --git a/src/Hakyll/Web/Template/Context.hs b/src/Hakyll/Web/Template/Context.hs
index 8aab989..1a9aba3 100644
--- a/src/Hakyll/Web/Template/Context.hs
+++ b/src/Hakyll/Web/Template/Context.hs
@@ -167,9 +167,10 @@ dateFieldWith locale key format = field key $ \i -> do
 -- | Parser to try to extract and parse the time from the @published@
 -- field or from the filename. See 'renderDateField' for more information.
 -- Exported for user convenience.
-getItemUTC :: TimeLocale        -- ^ Output time locale
+getItemUTC :: MonadMetadata m
+           => TimeLocale        -- ^ Output time locale
            -> Identifier        -- ^ Input page
-           -> Compiler UTCTime  -- ^ Parsed UTCTime
+           -> m UTCTime         -- ^ Parsed UTCTime
 getItemUTC locale id' = do
     metadata <- getMetadata id'
     let tryField k fmt = M.lookup k metadata >>= parseTime' fmt
@@ -180,7 +181,7 @@ getItemUTC locale id' = do
         [tryField "date"      fmt | fmt <- formats] ++
         [parseTime' "%Y-%m-%d" $ intercalate "-" $ take 3 $ splitAll "-" fn]
   where
-    empty'     = compilerThrow $ "Hakyll.Web.Template.Context.getItemUTC: " ++
+    empty'     = fail $ "Hakyll.Web.Template.Context.getItemUTC: " ++
         "could not parse time for " ++ show id'
     parseTime' = parseTime locale
     formats    =
diff --git a/src/Hakyll/Web/Template/List.hs b/src/Hakyll/Web/Template/List.hs
index 6d2a341..9571b9e 100644
--- a/src/Hakyll/Web/Template/List.hs
+++ b/src/Hakyll/Web/Template/List.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE TupleSections #-}
 --------------------------------------------------------------------------------
 -- | Provides an easy way to combine several items in a list. The applications
 -- are obvious:
@@ -16,15 +17,18 @@ module Hakyll.Web.Template.List
 
 
 --------------------------------------------------------------------------------
+import           Control.Monad               (liftM)
 import           Data.List                   (intersperse, sortBy)
 import           Data.Ord                    (comparing)
 import           System.FilePath             (takeBaseName)
+import           System.Locale               (defaultTimeLocale)
 
 
 --------------------------------------------------------------------------------
 import           Hakyll.Core.Compiler
 import           Hakyll.Core.Identifier
 import           Hakyll.Core.Item
+import           Hakyll.Core.Metadata
 import           Hakyll.Web.Template
 import           Hakyll.Web.Template.Context
 
@@ -56,11 +60,15 @@ applyJoinTemplateList delimiter tpl context items = do
 -- | Sort pages chronologically. This function assumes that the pages have a
 -- @year-month-day-title.extension@ naming scheme -- as is the convention in
 -- Hakyll.
-chronological :: [Item a] -> [Item a]
-chronological = sortBy $ comparing $ takeBaseName . toFilePath . itemIdentifier
-
+chronological :: MonadMetadata m => [Item a] -> m [Item a]
+chronological =
+    sortByM $ getItemUTC defaultTimeLocale . itemIdentifier
+  where
+    sortByM :: (Monad m, Ord k) => (a -> m k) -> [a] -> m [a]
+    sortByM f xs = liftM (map fst . sortBy (comparing snd)) $
+                   mapM (\x -> liftM (x,) (f x)) xs
 
 --------------------------------------------------------------------------------
 -- | The reverse of 'chronological'
-recentFirst :: [Item a] -> [Item a]
-recentFirst = reverse . chronological
+recentFirst :: (MonadMetadata m, Functor m) => [Item a] -> m [Item a]
+recentFirst = fmap reverse . chronological