28 lines
742 B
Haskell
28 lines
742 B
Haskell
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module NiceDate (niceDate) where
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import Text.Pandoc.Definition
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import qualified Data.Map.Strict as Map
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import Misc
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import Control.Monad.Writer
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import Data.Monoid
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niceDate :: Meta -> Meta
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niceDate (Meta m) =
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let (res', mdate) = run $ Map.alterF reformat' "date" m
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res = maybe m (\d -> Map.insert "date-iso" d res') mdate in
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Meta res
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type T = Writer (Alt Maybe MetaValue)
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run :: T a -> (a, Maybe MetaValue)
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run = fmap getAlt . runWriter
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reformat' :: Maybe MetaValue -> T (Maybe MetaValue)
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reformat' Nothing = pure Nothing
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reformat' (Just d) = do tell $ pure d; pure $ reformat d
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reformat :: MetaValue -> Maybe MetaValue
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reformat (toText -> Just txt) =
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MetaString . showDate <$> parseIsoDate txt
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reformat _ = Nothing
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