code:this is the codebase in haskell programming

main.hs

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+import Data.Conduit
+import Data.Conduit.Ical
+import Data.Time
+import Data.Text (Text)
+import Data.Icalendar
+import Data.Icalendar.Types
+import Data.Icalendar.Printer
+import System.Cron
+
+-- Parse iCalendar data from each subscription
+getEvents :: [Text] -> IO [VEvent]
+getEvents urls = do
+    events <- forM urls $ \url -> do
+        runResourceT $ parseIcs url $$ sinkIcs
+    return $ concat events
+
+-- Generate a new iCalendar file with the combined events
+generateCalendar :: [VEvent] -> Text
+generateCalendar events =
+    let cal = Calendar [Version 2, ProdId "my-calendar"]
+                (map (\event -> Component "VEVENT" [event]) events)
+    in printIcs cal
+
+
+-- Define the cron expression for the schedule
+cronExpression = "0,30 * * * *" -- runs every 30 minutes
+
+-- Define the task that should be executed on the schedule
+task :: IO ()
+task = do
+    putStrLn "Updating calendar..."
+    events <- getEvents urls -- get events from subscriptions
+    let newCalendar = generateCalendar events -- generate new calendar
+    -- write new calendar to file
+    writeFile "calendar.ics" (unpack newCalendar)
+    putStrLn "Calendar updated!"
+
+-- Run the task on the schedule
+main :: IO ()
+main = withCron cronExpression task