src/TSN/Picklers.hs

   1 -- | (Un)picklers for data types present in The Sports Network XML
   2 --   feed.
   3 --
   4 module TSN.Picklers (
   5   xp_date,
   6   xp_team_id )
   7 where
   8
   9 -- System imports.
  10 import Data.Time.Clock ( UTCTime )
  11 import Data.Time.Format ( formatTime, parseTime )
  12 import System.Locale ( defaultTimeLocale )
  13 import Text.Printf ( printf )
  14 import Text.Read ( readMaybe )
  15 import Text.XML.HXT.Arrow.Pickle (
  16   xpText,
  17   xpWrapMaybe )
  18 import Text.XML.HXT.Arrow.Pickle.Xml ( PU )
  19
  20
  21 -- | (Un)pickle a UTCTime without the time portion.
  22 --
  23 xp_date :: PU UTCTime
  24 xp_date =
  25   (to_date, from_date) `xpWrapMaybe` xpText
  26   where
  27     format = "%-m/%-d/%Y"
  28
  29     to_date :: String -> Maybe UTCTime
  30     to_date = parseTime defaultTimeLocale format
  31
  32     from_date :: UTCTime -> String
  33     from_date = formatTime defaultTimeLocale format
  34
  35
  36 -- | Parse a team_id. These are (so far!) three characters long, and
  37 --   not necessarily numeric. For simplicity, we return a 'String'
  38 --   rather than e.g. a @(Char, Char, Char)@. But unpickling will fail
  39 --   if the team_id is longer than three characters.
  40 --
  41 xp_team_id :: PU String
  42 xp_team_id =
  43   (to_team_id, from_team_id) `xpWrapMaybe` xpText
  44   where
  45     to_team_id :: String -> Maybe String
  46     to_team_id s
  47       | length s <= 3 = Just s
  48       | otherwise = Nothing
  49
  50     from_team_id :: String -> String
  51     from_team_id = id