-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | Cron datatypes and Attoparsec parser
--   
--   Cron data structure and Attoparsec parser. The idea is to embed it in
--   larger systems which want to roll their own scheduled tasks in a
--   format that people are used to. <a>System.Cron</a> is where all the
--   interesting datatypes live. You will also find <a>scheduleMatches</a>,
--   which you can use to compare a time against a <a>CronSchedule</a> to
--   see if an action needs to be performed. System.Cron.Parser is where
--   you will find the parsers <a>cronSchedule</a>, <a>crontabEntry</a> and
--   <a>cronTab</a>. To parse individual schedules up to full crontab
--   files.
@package cron
@version 0.5.0

module System.Cron.Internal.Describe.Types
data Descriptor
Descriptor :: String -> String -> String -> String -> String -> (Int -> String) -> String -> String -> (Int -> Maybe String) -> String -> Maybe String -> Descriptor
[pluralDesc] :: Descriptor -> String
[singularDesc] :: Descriptor -> String
[rangePrefix] :: Descriptor -> String
[rangeSuffix] :: Descriptor -> String
[rangeJoiner] :: Descriptor -> String
[displayItem] :: Descriptor -> Int -> String
[specificPrefix] :: Descriptor -> String
[specificSuffix] :: Descriptor -> String
[stepSpecificSuffix] :: Descriptor -> Int -> Maybe String
[listPrefix] :: Descriptor -> String
[listSuffix] :: Descriptor -> Maybe String
data Month
January :: Month
February :: Month
March :: Month
April :: Month
May :: Month
June :: Month
July :: Month
August :: Month
September :: Month
October :: Month
November :: Month
December :: Month
safeIntToMonth :: Int -> Month
data Weekday
Sunday :: Weekday
Monday :: Weekday
Tuesday :: Weekday
Wednesday :: Weekday
Thursday :: Weekday
Friday :: Weekday
Saturday :: Weekday
Sunday2 :: Weekday
safeIntToWeekDay :: Int -> Weekday
data Verbosity
Verbose :: Verbosity
NotVerbose :: Verbosity
data TimeFormat
Hour24 :: TimeFormat
Hour12 :: TimeFormat
data DescribedValue
Concrete :: String -> DescribedValue
Every :: String -> DescribedValue
data Time
ConcreteTime :: String -> Time
Other :: (Maybe DescribedValue) -> (Maybe DescribedValue) -> Time
data Description
Desc :: Time -> Maybe DescribedValue -> Maybe DescribedValue -> Maybe DescribedValue -> Description
[_time] :: Description -> Time
[_dom] :: Description -> Maybe DescribedValue
[_month] :: Description -> Maybe DescribedValue
[_dow] :: Description -> Maybe DescribedValue
instance GHC.Show.Show System.Cron.Internal.Describe.Types.Weekday
instance GHC.Enum.Bounded System.Cron.Internal.Describe.Types.Weekday
instance GHC.Enum.Enum System.Cron.Internal.Describe.Types.Weekday
instance GHC.Show.Show System.Cron.Internal.Describe.Types.Month
instance GHC.Enum.Bounded System.Cron.Internal.Describe.Types.Month
instance GHC.Enum.Enum System.Cron.Internal.Describe.Types.Month
instance GHC.Show.Show System.Cron.Internal.Describe.Types.DescribedValue
instance GHC.Show.Show System.Cron.Internal.Describe.Types.Time
instance GHC.Show.Show System.Cron.Internal.Describe.Types.Description


module System.Cron.Internal.Describe.Options

-- | Type that holds onto information for constructing options for
--   <a>describe</a>.
data OptionBuilder
Builder :: (Options -> Options) -> OptionBuilder

-- | Return a builder that creates the default options for <a>describe</a>.
--   The default options are: <a>notVerbose</a> and
--   <a>twelveHourFormat</a>.
defaultOpts :: OptionBuilder

-- | Return a builder that sets the options to use a 24-hour time format.
--   This changes how hours are described. Using the 24-hour format, all
--   hours are returned as their left-padded numeric value (01:00, 22:00,
--   etc)
twentyFourHourFormat :: OptionBuilder

-- | Return a builder that sets the options to use a 12-hour time format.
--   This changes how hours are described. Using the 12-hour format, all
--   hours are returned as their left-padded numeric value with their
--   period (01:00 AM, 10:00 PM, etc)
twelveHourFormat :: OptionBuilder

-- | Return a builder that sets the options to be verbose. A verbose
--   description doesn't eliminate unnecessary information. The only caveat
--   being that month information is only ever displayed if it isn't "*".
verbose :: OptionBuilder

-- | Return a builder that sets the options to not be verbose. All
--   information about the described cron schedule is returned. The only
--   caveat being that month information is only ever displayed if it isn't
--   "*".
notVerbose :: OptionBuilder
getOpts :: OptionBuilder -> Options
data Options
Opts :: TimeFormat -> Verbosity -> Options
[timeFormat] :: Options -> TimeFormat
[verbosity] :: Options -> Verbosity
instance Data.Default.Class.Default System.Cron.Internal.Describe.Options.Options
instance Data.Semigroup.Semigroup System.Cron.Internal.Describe.Options.OptionBuilder
instance GHC.Base.Monoid System.Cron.Internal.Describe.Options.OptionBuilder

module System.Cron.Internal.Describe.Time
newtype Minute
Minute :: Int -> Minute
newtype Hour
Hour :: Int -> Hour
format :: TimeFormat -> Minute -> Hour -> String

module System.Cron.Internal.Describe.Descriptors
minuteDescriptor :: Descriptor
hourDescriptor :: TimeFormat -> Descriptor
domDescriptor :: Descriptor
monthDescriptor :: Descriptor
dowDescriptor :: Descriptor

module System.Cron.Types

-- | Specification for a cron expression
data CronSchedule
CronSchedule :: MinuteSpec -> HourSpec -> DayOfMonthSpec -> MonthSpec -> DayOfWeekSpec -> CronSchedule

-- | Which minutes to run. First field in a cron specification.
[minute] :: CronSchedule -> MinuteSpec

-- | Which hours to run. Second field in a cron specification.
[hour] :: CronSchedule -> HourSpec

-- | Which days of the month to run. Third field in a cron specification.
[dayOfMonth] :: CronSchedule -> DayOfMonthSpec

-- | Which months to run. Fourth field in a cron specification.
[month] :: CronSchedule -> MonthSpec

-- | Which days of the week to run. Fifth field in a cron specification.
[dayOfWeek] :: CronSchedule -> DayOfWeekSpec

-- | Crontab file, omitting comments.
newtype Crontab
Crontab :: [CrontabEntry] -> Crontab
[crontabEntries] :: Crontab -> [CrontabEntry]

-- | Essentially a line in a crontab file. It is either a schedule with a
--   command after it or setting an environment variable (e.g. FOO=BAR)
data CrontabEntry
CommandEntry :: CronSchedule -> CronCommand -> CrontabEntry
EnvVariable :: Text -> Text -> CrontabEntry

-- | Minutes field of a cron expression
data MinuteSpec
newtype CronCommand
CronCommand :: Text -> CronCommand
[cronCommand] :: CronCommand -> Text
minuteSpec :: MinuteSpec -> CronField
mkMinuteSpec :: CronField -> Maybe MinuteSpec

-- | Hours field of a cron expression
data HourSpec
hourSpec :: HourSpec -> CronField
mkHourSpec :: CronField -> Maybe HourSpec

-- | Month field of a cron expression
data MonthSpec
monthSpec :: MonthSpec -> CronField
mkMonthSpec :: CronField -> Maybe MonthSpec

-- | Day of month field of a cron expression
data DayOfMonthSpec
dayOfMonthSpec :: DayOfMonthSpec -> CronField
mkDayOfMonthSpec :: CronField -> Maybe DayOfMonthSpec

-- | Day of week field of a cron expression
data DayOfWeekSpec
dayOfWeekSpec :: DayOfWeekSpec -> CronField
mkDayOfWeekSpec :: CronField -> Maybe DayOfWeekSpec

-- | Individual field of a cron expression.
data BaseField

-- | Matches anything
Star :: BaseField

-- | Matches a specific value (e.g. 1)
SpecificField' :: SpecificField -> BaseField

-- | Matches a range of values (e.g. 1-3)
RangeField' :: RangeField -> BaseField
data SpecificField
specificField :: SpecificField -> Int
mkSpecificField :: Int -> Maybe SpecificField
data RangeField
rfBegin :: RangeField -> Int
rfEnd :: RangeField -> Int
mkRangeField :: Int -> Int -> Maybe RangeField
data CronField
Field :: BaseField -> CronField

-- | Matches a list of expressions.
ListField :: (NonEmpty BaseField) -> CronField

-- | Matches a stepped expression, e.g. (*/2).
StepField' :: StepField -> CronField
data StepField
sfField :: StepField -> BaseField
sfStepping :: StepField -> Int
mkStepField :: BaseField -> Int -> Maybe StepField

-- | Shorthand for every January 1st at midnight. Parsed with @yearly, 0 0
--   1 1 *
yearly :: CronSchedule

-- | Shorthand for every 1st of the month at midnight. Parsed with
--   @monthly, 0 0 1 * *
monthly :: CronSchedule

-- | Shorthand for every day at midnight. Parsed with @daily, 0 0 * * *
daily :: CronSchedule

-- | Shorthand for every sunday at midnight. Parsed with @weekly, 0 0 * * 0
weekly :: CronSchedule

-- | Shorthand for every hour on the hour. Parsed with @hourly, 0 * * * *
hourly :: CronSchedule

-- | Shorthand for an expression that always matches. Parsed with * * * * *
everyMinute :: CronSchedule
serializeCronSchedule :: CronSchedule -> Text
serializeCrontab :: Crontab -> Text
instance GHC.Generics.Selector System.Cron.Types.S1_0_0Crontab
instance GHC.Generics.Constructor System.Cron.Types.C1_0Crontab
instance GHC.Generics.Datatype System.Cron.Types.D1Crontab
instance GHC.Generics.Constructor System.Cron.Types.C1_1CrontabEntry
instance GHC.Generics.Constructor System.Cron.Types.C1_0CrontabEntry
instance GHC.Generics.Datatype System.Cron.Types.D1CrontabEntry
instance GHC.Generics.Selector System.Cron.Types.S1_0_4CronSchedule
instance GHC.Generics.Selector System.Cron.Types.S1_0_3CronSchedule
instance GHC.Generics.Selector System.Cron.Types.S1_0_2CronSchedule
instance GHC.Generics.Selector System.Cron.Types.S1_0_1CronSchedule
instance GHC.Generics.Selector System.Cron.Types.S1_0_0CronSchedule
instance GHC.Generics.Constructor System.Cron.Types.C1_0CronSchedule
instance GHC.Generics.Datatype System.Cron.Types.D1CronSchedule
instance GHC.Generics.Selector System.Cron.Types.S1_0_0MinuteSpec
instance GHC.Generics.Constructor System.Cron.Types.C1_0MinuteSpec
instance GHC.Generics.Datatype System.Cron.Types.D1MinuteSpec
instance GHC.Generics.Selector System.Cron.Types.S1_0_0HourSpec
instance GHC.Generics.Constructor System.Cron.Types.C1_0HourSpec
instance GHC.Generics.Datatype System.Cron.Types.D1HourSpec
instance GHC.Generics.Selector System.Cron.Types.S1_0_0DayOfMonthSpec
instance GHC.Generics.Constructor System.Cron.Types.C1_0DayOfMonthSpec
instance GHC.Generics.Datatype System.Cron.Types.D1DayOfMonthSpec
instance GHC.Generics.Selector System.Cron.Types.S1_0_0MonthSpec
instance GHC.Generics.Constructor System.Cron.Types.C1_0MonthSpec
instance GHC.Generics.Datatype System.Cron.Types.D1MonthSpec
instance GHC.Generics.Selector System.Cron.Types.S1_0_0DayOfWeekSpec
instance GHC.Generics.Constructor System.Cron.Types.C1_0DayOfWeekSpec
instance GHC.Generics.Datatype System.Cron.Types.D1DayOfWeekSpec
instance GHC.Generics.Constructor System.Cron.Types.C1_2CronField
instance GHC.Generics.Constructor System.Cron.Types.C1_1CronField
instance GHC.Generics.Constructor System.Cron.Types.C1_0CronField
instance GHC.Generics.Datatype System.Cron.Types.D1CronField
instance GHC.Generics.Selector System.Cron.Types.S1_0_1StepField
instance GHC.Generics.Selector System.Cron.Types.S1_0_0StepField
instance GHC.Generics.Constructor System.Cron.Types.C1_0StepField
instance GHC.Generics.Datatype System.Cron.Types.D1StepField
instance GHC.Generics.Constructor System.Cron.Types.C1_2BaseField
instance GHC.Generics.Constructor System.Cron.Types.C1_1BaseField
instance GHC.Generics.Constructor System.Cron.Types.C1_0BaseField
instance GHC.Generics.Datatype System.Cron.Types.D1BaseField
instance GHC.Generics.Selector System.Cron.Types.S1_0_1RangeField
instance GHC.Generics.Selector System.Cron.Types.S1_0_0RangeField
instance GHC.Generics.Constructor System.Cron.Types.C1_0RangeField
instance GHC.Generics.Datatype System.Cron.Types.D1RangeField
instance GHC.Generics.Selector System.Cron.Types.S1_0_0SpecificField
instance GHC.Generics.Constructor System.Cron.Types.C1_0SpecificField
instance GHC.Generics.Datatype System.Cron.Types.D1SpecificField
instance GHC.Generics.Selector System.Cron.Types.S1_0_0CronCommand
instance GHC.Generics.Constructor System.Cron.Types.C1_0CronCommand
instance GHC.Generics.Datatype System.Cron.Types.D1CronCommand
instance GHC.Generics.Generic System.Cron.Types.Crontab
instance GHC.Classes.Eq System.Cron.Types.Crontab
instance GHC.Generics.Generic System.Cron.Types.CrontabEntry
instance GHC.Classes.Eq System.Cron.Types.CrontabEntry
instance GHC.Generics.Generic System.Cron.Types.CronSchedule
instance GHC.Classes.Eq System.Cron.Types.CronSchedule
instance GHC.Generics.Generic System.Cron.Types.MinuteSpec
instance System.Cron.Types.ShowT System.Cron.Types.MinuteSpec
instance GHC.Classes.Eq System.Cron.Types.MinuteSpec
instance GHC.Generics.Generic System.Cron.Types.HourSpec
instance System.Cron.Types.ShowT System.Cron.Types.HourSpec
instance GHC.Classes.Eq System.Cron.Types.HourSpec
instance GHC.Generics.Generic System.Cron.Types.DayOfMonthSpec
instance System.Cron.Types.ShowT System.Cron.Types.DayOfMonthSpec
instance GHC.Classes.Eq System.Cron.Types.DayOfMonthSpec
instance GHC.Generics.Generic System.Cron.Types.MonthSpec
instance System.Cron.Types.ShowT System.Cron.Types.MonthSpec
instance GHC.Classes.Eq System.Cron.Types.MonthSpec
instance GHC.Generics.Generic System.Cron.Types.DayOfWeekSpec
instance System.Cron.Types.ShowT System.Cron.Types.DayOfWeekSpec
instance GHC.Classes.Eq System.Cron.Types.DayOfWeekSpec
instance GHC.Generics.Generic System.Cron.Types.CronField
instance GHC.Generics.Generic System.Cron.Types.StepField
instance GHC.Classes.Eq System.Cron.Types.StepField
instance GHC.Generics.Generic System.Cron.Types.BaseField
instance GHC.Classes.Eq System.Cron.Types.BaseField
instance GHC.Generics.Generic System.Cron.Types.RangeField
instance GHC.Classes.Eq System.Cron.Types.RangeField
instance GHC.Generics.Generic System.Cron.Types.SpecificField
instance System.Cron.Types.ShowT System.Cron.Types.SpecificField
instance GHC.Classes.Eq System.Cron.Types.SpecificField
instance GHC.Generics.Generic System.Cron.Types.CronCommand
instance System.Cron.Types.ShowT System.Cron.Types.CronCommand
instance GHC.Classes.Ord System.Cron.Types.CronCommand
instance GHC.Classes.Eq System.Cron.Types.CronCommand
instance GHC.Show.Show System.Cron.Types.CronCommand
instance System.Cron.Types.ShowT Data.Text.Internal.Text
instance System.Cron.Types.ShowT GHC.Types.Int
instance GHC.Show.Show System.Cron.Types.CronSchedule
instance System.Cron.Types.ShowT System.Cron.Types.CronSchedule
instance System.Cron.Types.ShowT System.Cron.Types.Crontab
instance GHC.Show.Show System.Cron.Types.Crontab
instance System.Cron.Types.ShowT System.Cron.Types.CrontabEntry
instance GHC.Show.Show System.Cron.Types.CrontabEntry
instance GHC.Show.Show System.Cron.Types.MinuteSpec
instance GHC.Show.Show System.Cron.Types.HourSpec
instance GHC.Show.Show System.Cron.Types.DayOfMonthSpec
instance GHC.Show.Show System.Cron.Types.MonthSpec
instance GHC.Show.Show System.Cron.Types.DayOfWeekSpec
instance System.Cron.Types.ShowT System.Cron.Types.BaseField
instance GHC.Show.Show System.Cron.Types.BaseField
instance GHC.Show.Show System.Cron.Types.SpecificField
instance System.Cron.Types.ShowT System.Cron.Types.RangeField
instance GHC.Show.Show System.Cron.Types.RangeField
instance GHC.Classes.Eq System.Cron.Types.CronField
instance System.Cron.Types.ShowT System.Cron.Types.CronField
instance GHC.Show.Show System.Cron.Types.CronField
instance System.Cron.Types.ShowT System.Cron.Types.StepField
instance GHC.Show.Show System.Cron.Types.StepField


-- | Attoparsec parser combinator for cron schedules. See cron
--   documentation for how those are formatted.
--   
--   <pre>
--   import System.Cron.Parser
--   
--   main :: IO ()
--   main = do
--     print $ parseCronSchedule "*/2 * 3 * 4,5,6"
--   </pre>
module System.Cron.Parser

-- | Attoparsec Parser for a cron schedule. Complies fully with the
--   standard cron format. Also includes the following shorthand formats
--   which cron also supports: @yearly, @monthly, @weekly, @daily, @hourly.
--   Note that this parser will fail if there is extraneous input. This is
--   to prevent things like extra fields. If you want a more lax parser,
--   use <a>cronScheduleLoose</a>, which is fine with extra input.
cronSchedule :: Parser CronSchedule

-- | Same as <a>cronSchedule</a> but does not fail on extraneous input.
cronScheduleLoose :: Parser CronSchedule

-- | Parses a full crontab file, omitting comments and including
--   environment variable sets (e.g FOO=BAR).
crontab :: Parser Crontab

-- | Parses an individual crontab line, which is either a scheduled command
--   or an environmental variable set.
crontabEntry :: Parser CrontabEntry
parseCronSchedule :: Text -> Either String CronSchedule
parseCrontab :: Text -> Either String Crontab
parseCrontabEntry :: Text -> Either String CrontabEntry

module System.Cron.Internal.Check

-- | Will return the next time from the given starting point where this
--   schedule will match. Returns Nothing if the schedule will never match.
--   Note that this function is not inclusive of the given time: the result
--   will always be at least 1 minute beyond the given time. This is
--   usually used to implement absolute timestamp schedulers. If you need
--   to see multiple matches ahead, just keep feeding the result into
--   nextMatch. Note that because nextMatch only returns Nothing on a
--   schedule that will *never* be matched, it is safe to assume that if a
--   schedule returns a Just once, it will always return a Just.
nextMatch :: CronSchedule -> UTCTime -> Maybe UTCTime
nextMatches :: [Day] -> Expanded -> UTCTime -> [UTCTime]
dowMatch :: UTCTime -> EField -> Bool

-- | ISO8601 maps Sunday as 7 and Monday as 1, we want Sunday as 0
getDOW :: Day -> Int
validDays :: EField -> EField -> Day -> [Day]

-- | Guarantees: the Expanded will be satisfiable (no invalid dates, no
--   empties). dow 7 will be normalized to 0 (Sunday)
expand :: CronSchedule -> Maybe Expanded
expandF :: (Int, Int) -> CronField -> Maybe EField
expandBFStepped :: (Int, Int) -> BaseField -> Int -> Maybe EField
fillTo :: (Int, Int) -> Int -> [Int]
expandBF :: (Int, Int) -> BaseField -> Maybe EField
validTODs :: EField -> EField -> [DiffTime]
todToDiffTime :: Int -> Int -> DiffTime
timeOfDay :: DiffTime -> (Int, Int)
hasValidForMonth :: Int -> EField -> Bool
data Expanded
Expanded :: EField -> EField -> EField -> EField -> EField -> Expanded
[minF] :: Expanded -> EField
[hourF] :: Expanded -> EField
[domF] :: Expanded -> EField
[monthF] :: Expanded -> EField
[dowF] :: Expanded -> EField
type EField = NonEmpty Int

-- | Does the given cron schedule match for the given timestamp? This is
--   usually used for implementing polling-type schedulers like cron
--   itself.
scheduleMatches :: CronSchedule -> UTCTime -> Bool
restricted :: CronField -> Bool
isStar :: CronField -> Bool
instance GHC.Show.Show System.Cron.Internal.Check.Expanded


-- | <pre>
--   main :: IO ()
--   main = do
--          ...
--          tids &lt;- execSchedule $ do
--              addJob job1 "* * * * *"
--              addJob job2 "0 * * * *"
--          print tids
--          ...
--   
--   job1 :: IO ()
--   job1 = putStrLn "Job 1"
--   
--   job2 :: IO ()
--   job2 = putStrLn "Job 2"
--   </pre>
module System.Cron.Schedule

-- | Scheduling Monad
data Job
Job :: CronSchedule -> (IO ()) -> Job
data ScheduleError
ParseError :: String -> ScheduleError
type Schedule = ScheduleT Identity
newtype ScheduleT m a
ScheduleT :: StateT Jobs (ExceptT ScheduleError m) a -> ScheduleT m a
[unSchedule] :: ScheduleT m a -> StateT Jobs (ExceptT ScheduleError m) a
class MonadSchedule m
addJob :: MonadSchedule m => IO () -> String -> m ()
runSchedule :: Schedule a -> Either ScheduleError (a, [Job])
runScheduleT :: ScheduleT m a -> m (Either ScheduleError (a, [Job]))

-- | Schedule all of the jobs to run at appropriate intervals. Each job
--   that is launched gets a scheduling thread to itself. Each time a
--   scheduling thread launches a job, the job is forked onto a new thread.
--   This means that if a job throws an excpetion in IO, its thread will be
--   killed, but it will continue to be scheduled in the future.
execSchedule :: Schedule () -> IO [ThreadId]
instance GHC.Base.Monad m => Control.Monad.Error.Class.MonadError System.Cron.Schedule.ScheduleError (System.Cron.Schedule.ScheduleT m)
instance GHC.Base.Monad m => Control.Monad.State.Class.MonadState System.Cron.Schedule.Jobs (System.Cron.Schedule.ScheduleT m)
instance GHC.Base.Monad m => GHC.Base.Monad (System.Cron.Schedule.ScheduleT m)
instance GHC.Base.Monad m => GHC.Base.Applicative (System.Cron.Schedule.ScheduleT m)
instance GHC.Base.Functor m => GHC.Base.Functor (System.Cron.Schedule.ScheduleT m)
instance GHC.Show.Show System.Cron.Schedule.ScheduleError
instance GHC.Show.Show System.Cron.Schedule.Job
instance GHC.Base.Monad m => System.Cron.Schedule.MonadSchedule (System.Cron.Schedule.ScheduleT m)

module System.Cron.Internal.Describe.Utils
viewHour :: HourSpec -> Maybe Hour
viewMinute :: MinuteSpec -> Maybe Minute
viewMinuteRange :: MinuteSpec -> Maybe (Minute, Minute)
viewHourList :: HourSpec -> Maybe (NonEmpty BaseField)
allWords :: [String] -> String
cap :: String -> String
joinWords :: [String] -> String


-- | <pre>
--   import System.Cron
--   
--   main :: IO ()
--   main = do
--     let Right cs1 = parseCronSchedule "*/2 * 3 * 4,5,6"
--     print $ describe defaultOpts cs1
--   
--     let Right cs2 = parseCronSchedule "*/2 12 3 * 4,5,6"
--     print $ describe (twentyFourHourFormat &lt;&gt; verbose) cs2
--   </pre>
module System.Cron.Describe

-- | Return a builder that creates the default options for <a>describe</a>.
--   The default options are: <a>notVerbose</a> and
--   <a>twelveHourFormat</a>.
defaultOpts :: OptionBuilder

-- | Return a builder that sets the options to use a 24-hour time format.
--   This changes how hours are described. Using the 24-hour format, all
--   hours are returned as their left-padded numeric value (01:00, 22:00,
--   etc)
twentyFourHourFormat :: OptionBuilder

-- | Return a builder that sets the options to use a 12-hour time format.
--   This changes how hours are described. Using the 12-hour format, all
--   hours are returned as their left-padded numeric value with their
--   period (01:00 AM, 10:00 PM, etc)
twelveHourFormat :: OptionBuilder

-- | Return a builder that sets the options to be verbose. A verbose
--   description doesn't eliminate unnecessary information. The only caveat
--   being that month information is only ever displayed if it isn't "*".
verbose :: OptionBuilder

-- | Return a builder that sets the options to not be verbose. All
--   information about the described cron schedule is returned. The only
--   caveat being that month information is only ever displayed if it isn't
--   "*".
notVerbose :: OptionBuilder

-- | Type that holds onto information for constructing options for
--   <a>describe</a>.
data OptionBuilder

-- | Given an <a>OptionBuilder</a> and a <a>CronSchedule</a> parsed with
--   <a>parseCronSchedule</a>, return a human-readable string describing
--   when that schedule will match.
describe :: OptionBuilder -> CronSchedule -> String

module System.Cron

-- | Does the given cron schedule match for the given timestamp? This is
--   usually used for implementing polling-type schedulers like cron
--   itself.
scheduleMatches :: CronSchedule -> UTCTime -> Bool

-- | Will return the next time from the given starting point where this
--   schedule will match. Returns Nothing if the schedule will never match.
--   Note that this function is not inclusive of the given time: the result
--   will always be at least 1 minute beyond the given time. This is
--   usually used to implement absolute timestamp schedulers. If you need
--   to see multiple matches ahead, just keep feeding the result into
--   nextMatch. Note that because nextMatch only returns Nothing on a
--   schedule that will *never* be matched, it is safe to assume that if a
--   schedule returns a Just once, it will always return a Just.
nextMatch :: CronSchedule -> UTCTime -> Maybe UTCTime