46 lines
1.5 KiB
Haskell
46 lines
1.5 KiB
Haskell
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import Text.Pandoc.Definition
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import Data.Map.Strict (Map)
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import qualified Data.Map.Strict as Map
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import Data.Time
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import Text.Pandoc.JSON
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import Data.Text (Text, unpack, pack)
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import Data.Char (toLower)
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main :: IO ()
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main = toJSONFilter \(Pandoc (Meta m) body) -> do
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m' <- niceDate m
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pure $ Pandoc (Meta m') body
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niceDate :: Map Text MetaValue -> IO (Map Text MetaValue)
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niceDate = Map.alterF reformat "date"
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reformat :: Maybe MetaValue -> IO (Maybe MetaValue)
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reformat Nothing = pure Nothing
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reformat (Just (toText -> Just txt)) = do
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-- extra '-'s in %-m and %-d to allow leading zeroes to be skipped
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date <- parseTimeM True defaultTimeLocale "%Y-%-m-%-d" $ unpack txt
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let str = formatTime defaultTimeLocale "%A %-e %B %Y" (date :: Day)
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pure $ Just $ MetaString $ pack $ map toLower str
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reformat (Just d) = fail $ "date is\n" <> show d <> "\nwanted a string"
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toText :: MetaValue -> Maybe Text
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toText (MetaString str) = Just str
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toText (MetaInlines is) = foldMap inlineText is
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toText (MetaBlocks bs) = foldMap blockText bs
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toText _ = Nothing
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inlineText :: Inline -> Maybe Text
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inlineText (Str txt) = Just txt
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inlineText Space = Just " "
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inlineText SoftBreak = Just " "
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inlineText LineBreak = Just " "
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inlineText (RawInline _ txt) = Just txt
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inlineText _ = Nothing
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blockText :: Block -> Maybe Text
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blockText (Plain is) = foldMap inlineText is
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blockText (Para is) = foldMap inlineText is
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blockText Null = Just ""
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blockText (RawBlock _ txt) = Just txt
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blockText _ = Nothing
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