    -- Note: this file derives from old-locale:System.Locale.hs, which is copyright (c) The University of Glasgow 2001

    module Data.Time.Format.Locale (

        TimeLocale(..)

        , defaultTimeLocale

        , iso8601DateFormat
        , rfc822DateFormat
        )
    where

    import Data.Time.LocalTime

    data TimeLocale = TimeLocale {
            -- |full and abbreviated week days, starting with Sunday
            wDays  :: [(String, String)],
            -- |full and abbreviated months
            months :: [(String, String)],
            -- |AM\/PM symbols
            amPm   :: (String, String),
            -- |formatting strings
            dateTimeFmt, dateFmt,
            timeFmt, time12Fmt :: String,
            -- |time zones known by name
            knownTimeZones :: [TimeZone]
            } deriving (Eq, Ord, Show)

    -- | Locale representing American usage.
    --
    -- 'knownTimeZones' contains only the ten time-zones mentioned in RFC 822 sec. 5:
    -- \"UT\", \"GMT\", \"EST\", \"EDT\", \"CST\", \"CDT\", \"MST\", \"MDT\", \"PST\", \"PDT\".
    -- Note that the parsing functions will regardless parse single-letter military time-zones and +HHMM format.
    defaultTimeLocale :: TimeLocale
    defaultTimeLocale =  TimeLocale {
            wDays  = [("Sunday",   "Sun"),  ("Monday",    "Mon"),
                      ("Tuesday",  "Tue"),  ("Wednesday", "Wed"),
                      ("Thursday", "Thu"),  ("Friday",    "Fri"),
                      ("Saturday", "Sat")],

            months = [("January",   "Jan"), ("February",  "Feb"),
                      ("March",     "Mar"), ("April",     "Apr"),
                      ("May",       "May"), ("June",      "Jun"),
                      ("July",      "Jul"), ("August",    "Aug"),
                      ("September", "Sep"), ("October",   "Oct"),
                      ("November",  "Nov"), ("December",  "Dec")],

            amPm = ("AM", "PM"),
            dateTimeFmt = "%a %b %e %H:%M:%S %Z %Y",
            dateFmt = "%m/%d/%y",
            timeFmt = "%H:%M:%S",
            time12Fmt = "%I:%M:%S %p",
            knownTimeZones =
                [
                TimeZone 0 False "UT",
                TimeZone 0 False "GMT",
                TimeZone (-5 * 60) False "EST",
                TimeZone (-4 * 60) True "EDT",
                TimeZone (-6 * 60) False "CST",
                TimeZone (-5 * 60) True "CDT",
                TimeZone (-7 * 60) False "MST",
                TimeZone (-6 * 60) True "MDT",
                TimeZone (-8 * 60) False "PST",
                TimeZone (-7 * 60) True "PDT"
                ]
            }

    {- | Construct format string according to <http://en.wikipedia.org/wiki/ISO_8601 ISO-8601>.

    The @Maybe String@ argument allows to supply an optional time specification. E.g.:

    @
    'iso8601DateFormat' Nothing            == "%Y-%m-%d"           -- i.e. @/YYYY-MM-DD/@
    'iso8601DateFormat' (Just "%H:%M:%S")  == "%Y-%m-%dT%H:%M:%S"  -- i.e. @/YYYY-MM-DD/T/HH:MM:SS/@
    @
    -}

    iso8601DateFormat :: Maybe String -> String
    iso8601DateFormat mTimeFmt =
        "%Y-%m-%d" ++ case mTimeFmt of
                 Nothing  -> ""
                 Just fmt -> 'T' : fmt

    -- | Format string according to <http://tools.ietf.org/html/rfc822#section-5 RFC822>.
    rfc822DateFormat :: String
    rfc822DateFormat = "%a, %_d %b %Y %H:%M:%S %Z"