Add Haddock documentation for most functions and types.

[dead/halcyon.git] / src / Main.hs

diff --git a/src/Main.hs b/src/Main.hs
index 8c2f20bffeea26dff632baf8519d39ca50b8cf99..f42f2ce57738a4899005d146bf0700b46c88a377 100644 (file)
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -7,29 +7,40 @@ import System.Exit (ExitCode(..), exitWith)
 import System.IO (hPutStrLn, stderr)
 
 import CommandLine
+import ExitCodes
 import Mail
 import Twitter.Http
 import Twitter.Status
 import Twitter.User
 
-exit_args_parse_failed :: Int
-exit_args_parse_failed = 1
 
--- The length of all calls to sleep, in seconds.
+-- |The length of all calls to sleep (or threadDelay), in seconds.
 heartbeat :: Int
 heartbeat = 600
 
+-- |A wrapper around threadDelay which takes seconds instead of
+-- microseconds as its argument.
 thread_sleep :: Int -> IO ()
-thread_sleep microseconds = do
-  let seconds = microseconds * (10 ^ (6 :: Int))
-  threadDelay seconds
+thread_sleep seconds = do
+  let microseconds = seconds * (10 ^ (6 :: Int))
+  threadDelay microseconds
 
 
+-- |Given a 'Message' and a 'Status', update that message's body and
+-- subject with the information contained in the status. Returns the
+-- updated message.
 message_from_status :: Message -> Status -> Message
 message_from_status message status =
     message { subject = "Twat: " ++ (screen_name (user status)),
               body    = (pretty_print status) }
 
+
+-- |This is the main recursive loop. It takes a username, a
+-- latest_status_id, and optionally a 'Message' as arguments. The
+-- latest_status_id is the last status (that we know of) to be posted
+-- to username's Twitter account. If we find any newer statuses when
+-- we check, they are printed and optionally emailed (if a 'Message'
+-- was supplied). Then, the process repeats.
 recurse :: String -> Integer -> (Maybe Message) -> IO ()
 recurse username latest_status_id maybe_message = do
     thread_sleep heartbeat
@@ -60,6 +71,8 @@ recurse username latest_status_id maybe_message = do
              return ()
 
 
+-- |Try continually to download username's timeline, and determine the
+-- latest status id to be posted once we have done so.
 get_latest_status_id :: String -> IO Integer
 get_latest_status_id username = do
   xmldata <- get_user_timeline username
@@ -78,13 +91,21 @@ get_latest_status_id username = do
 
 
 
+-- |This function wraps two steps. First, we need to find the latest
+-- status id posted by username. Once we have that, we can begin the
+-- recursive loop that checks for updates forever. The message
+-- argument is optional and is passed to recurse in case the updates
+-- should be emailed.
 run_twat :: Maybe Message -> String -> IO ()
-run_twat message username = do  
-  latest_status_id <- get_latest_status_id username  
+run_twat message username = do
+  latest_status_id <- get_latest_status_id username
   recurse username latest_status_id message
   return ()
 
 
+-- |The main function just parses the command-line arguments and then
+-- forks off calls to 'run_twat' for each supplied username. After
+-- forking, main loops forever.
 main :: IO ()
 main = do
   errors <- parse_errors
@@ -123,7 +144,7 @@ main = do
 
   -- Execute run_twat on each username in a new thread.
   mapM (forkIO . (run_twat message)) usernames
-           
+
   forever $ do
     -- This thread (the one executing main) doesn't do anything,
     -- but when it terminates, so do all the threads we forked.