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   xp_time )
   8 where
   9
  10 -- System imports.
  11 import Data.Time.Clock ( UTCTime )
  12 import Data.Time.Format ( formatTime, parseTime )
  13 import System.Locale ( defaultTimeLocale )
  14 import Text.XML.HXT.Arrow.Pickle (
  15   xpText,
  16   xpWrapMaybe )
  17 import Text.XML.HXT.Arrow.Pickle.Xml ( PU )
  18
  19
  20 -- | (Un)pickle a UTCTime without the time portion.
  21 --
  22 xp_date :: PU UTCTime
  23 xp_date =
  24   (to_date, from_date) `xpWrapMaybe` xpText
  25   where
  26     format = "%-m/%-d/%Y"
  27
  28     to_date :: String -> Maybe UTCTime
  29     to_date = parseTime defaultTimeLocale format
  30
  31     from_date :: UTCTime -> String
  32     from_date = formatTime defaultTimeLocale format
  33
  34
  35 -- | (Un)pickle a UTCTime without the date portion.
  36 --
  37 xp_time :: PU UTCTime
  38 xp_time =
  39   (to_time, from_time) `xpWrapMaybe` xpText
  40   where
  41     format = "%I:%M %p"
  42
  43     to_time :: String -> Maybe UTCTime
  44     to_time = parseTime defaultTimeLocale format
  45
  46     from_time :: UTCTime -> String
  47     from_time = formatTime defaultTimeLocale format
  48
  49
  50
  51 -- | Parse a team_id. These are (so far!) three characters long, and
  52 --   not necessarily numeric. For simplicity, we return a 'String'
  53 --   rather than e.g. a @(Char, Char, Char)@. But unpickling will fail
  54 --   if the team_id is longer than three characters.
  55 --
  56 xp_team_id :: PU String
  57 xp_team_id =
  58   (to_team_id, from_team_id) `xpWrapMaybe` xpText
  59   where
  60     to_team_id :: String -> Maybe String
  61     to_team_id s
  62       | length s <= 3 = Just s
  63       | otherwise = Nothing
  64
  65     from_team_id :: String -> String
  66     from_team_id = id