Add exceptions

app/Main.hs

@@ -4,7 +4,7 @@ module Main(main, parseTask, serializeTask, getPriority, comparePriority, TaskMa
 
 import System.IO
 import System.Directory
-import Data.Text (Text, pack, unpack, isInfixOf, lines, unlines, strip)
+import Data.Text (Text, pack, unpack, isInfixOf, lines, unlines, strip, splitOn)
 import qualified Data.Text.IO as TIO
 import qualified Data.ByteString as BS
 import qualified Data.ByteString.Char8 as BSC
@@ -14,6 +14,7 @@ import Data.Ord (comparing)
 import Data.Char (isAlpha)
 import qualified Data.Map as Map
 import Data.Function (on)
+import Control.Exception (catch, IOException)
 
 todoFile :: FilePath
 todoFile = "todo.txt"
@@ -44,12 +45,17 @@ displayTasks = do
     exists <- doesFileExist todoFile
     if exists
         then do
-            contents <- BSC.readFile todoFile
-            let taskMap = parseTask (pack (BSC.unpack contents))
+            contents <- catch (TIO.readFile todoFile) handleReadError
+            let taskMap = parseTask contents
             putStrLn "Tasks:"
             mapM_ (putStrLn . showTask) (Map.toList taskMap)
         else putStrLn "No tasks found."
     main
+  where
+    handleReadError :: IOException -> IO Text
+    handleReadError e = do
+        putStrLn $ "Error reading file: " ++ show e
+        return ""
 
 addTask :: IO ()
 addTask = do
@@ -59,14 +65,22 @@ addTask = do
     exists <- doesFileExist todoFile
     if exists
         then do
-            contents <- BSC.readFile todoFile
-            let taskMap = parseTask (pack (BSC.unpack contents))
+            contents <- catch (TIO.readFile todoFile) handleReadError
+            let taskMap = parseTask contents
                 newId = if Map.null taskMap then 1 else fst (Map.findMax taskMap) + 1
                 newTaskMap = Map.insert newId (pack task) taskMap
-            BSC.writeFile todoFile (BSC.pack (unpack (serializeTask newTaskMap)))
-        else BSC.writeFile todoFile (BSC.pack (task <> "\n"))
+            catch (TIO.writeFile todoFile (serializeTask newTaskMap)) handleWriteError
+        else catch (TIO.writeFile todoFile (pack task <> "\n")) handleWriteError
     putStrLn "Task added."
     main
+  where
+    handleReadError :: IOException -> IO Text
+    handleReadError e = do
+        putStrLn $ "Error reading file: " ++ show e
+        return ""
+
+    handleWriteError :: IOException -> IO ()
+    handleWriteError e = putStrLn $ "Error writing file: " ++ show e
 
 filterTasksByTag :: IO ()
 filterTasksByTag = do
@@ -76,26 +90,36 @@ filterTasksByTag = do
     exists <- doesFileExist todoFile
     if exists
         then do
-            contents <- TIO.readFile todoFile
+            contents <- catch (TIO.readFile todoFile) handleReadError
             let taskMap = parseTask contents
                 filteredTasks = Map.filter (isInfixOf (pack tag)) taskMap
             putStrLn "Filtered tasks:"
             mapM_ (putStrLn . showTask) (Map.toList filteredTasks)
         else putStrLn "No tasks found."
     main
+  where
+    handleReadError :: IOException -> IO Text
+    handleReadError e = do
+        putStrLn $ "Error reading file: " ++ show e
+        return ""
 
 sortTasksByPriority :: IO ()
 sortTasksByPriority = do
     exists <- doesFileExist todoFile
     if exists
         then do
-            contents <- TIO.readFile todoFile
+            contents <- catch (TIO.readFile todoFile) handleReadError
             let taskMap = parseTask contents
                 sortedTasks = sortBy (comparePriority `on` snd) (Map.toList taskMap)
             putStrLn "Sorted tasks by priority:"
             mapM_ (putStrLn . showTask) sortedTasks
         else putStrLn "No tasks found."
     main
+  where
+    handleReadError :: IOException -> IO Text
+    handleReadError e = do
+        putStrLn $ "Error reading file: " ++ show e
+        return ""
 
 comparePriority :: Text -> Text -> Ordering
 comparePriority t1 t2 = comparing getPriority t1 t2