feat (IO.Markdown): added warning if file could not be fully parsed

app/Main.hs

@@ -11,4 +11,10 @@ main :: IO ()
 main = do
     config <- setup
     (exists, path) <- T.exists config
-    when exists $ create path <$> T.readFile config path >>= go config
+
+    when exists $ do
+        content <- T.readFile config path
+
+        case content of
+            Right lists -> go config $ create path lists
+            Left err -> putStrLn $ path ++ ": " ++ err

roadmap.md

@@ -45,7 +45,6 @@
 ## In Progress
 
 - One bad config line stops all config from working - needs to merge with defaultConfig
-- Display a warning if any line of the file could not be parsed - otherwise could lead to data loss
 
 ## Done
 
@@ -139,3 +138,4 @@
     * ~Change sub-list: e.g. from "    *" to "-"~
 - Feels sluggish in sub-task view - cache main view?
 - Leaving search only refreshes current list
+- Display a warning if any line of the file could not be parsed - otherwise could lead to data loss

src/IO/Markdown.hs

@@ -5,7 +5,8 @@ module IO.Markdown (
     trimListItem
 ) where
 
-import Data.Text (Text, drop, append, null, lines, isPrefixOf, strip, dropAround, snoc)
+import Data.Text as T (Text, drop, append, null, lines, isPrefixOf, strip, dropAround, snoc)
+import Data.List (intercalate)
 import Data.Text.Encoding (encodeUtf8, decodeUtf8With)
 
 import Data.Taskell.Lists (Lists, newList, appendToLast)
@@ -20,16 +21,16 @@ import IO.Config (Config, MarkdownConfig, markdown, titleOutput, taskOutput, sub
 
 -- parse code
 trimListItem :: Text -> Text
-trimListItem = strip . Data.Text.drop 1
+trimListItem = strip . T.drop 1
 
 trimTitle :: Text -> Text
-trimTitle = strip . Data.Text.drop 2
+trimTitle = strip . T.drop 2
 
 trimTask :: Text -> Task
 trimTask = new . trimListItem
 
 trimTilde :: Text -> Text
-trimTilde = strip . Data.Text.dropAround (== '~')
+trimTilde = strip . T.dropAround (== '~')
 
 addSubItem :: Text -> Lists -> Lists
 addSubItem t ls = adjust' updateList i ls
@@ -39,21 +40,32 @@ addSubItem t ls = adjust' updateList i ls
           updateList l = updateFn j (addSubTask st) l
             where j = count l - 1
 
-start :: MarkdownConfig -> Lists -> Text -> Lists
-start config ls s | titleOutput config `snoc` ' ' `isPrefixOf` s = newList (trimTitle s) ls
-                  | taskOutput config `snoc` ' ' `isPrefixOf` s = appendToLast (trimTask s) ls
-                  | subtaskOutput config `snoc` ' ' `isPrefixOf` s = addSubItem (trimListItem $ strip s) ls
-                  | otherwise = ls
+start :: MarkdownConfig -> (Lists, [Int]) -> (Text, Int) -> (Lists, [Int])
+start config (ls, errs) (s, li)
+    | titleOutput config `snoc` ' ' `isPrefixOf` s = (newList (trimTitle s) ls, errs)
+    | taskOutput config `snoc` ' ' `isPrefixOf` s = (appendToLast (trimTask s) ls, errs)
+    | subtaskOutput config `snoc` ' ' `isPrefixOf` s = (addSubItem (trimListItem $ strip s) ls, errs)
+    | not (T.null (strip s)) = (ls, errs ++ [li])
+    | otherwise = (ls, errs)
 
 decodeError :: String -> Maybe Word8 -> Maybe Char
 decodeError _ _ = Just '\65533'
 
-parse :: Config -> ByteString -> Lists
-parse config s = foldl' (start (markdown config)) empty $ Data.Text.lines $ decodeUtf8With decodeError s
+parse :: Config -> ByteString -> Either String Lists
+parse config s = do
+    let lns = T.lines $ decodeUtf8With decodeError s
+    let fn = start (markdown config)
+    let acc = (empty, [])
+    let (lists, errs) = foldl' fn acc $ zip lns [1..]
+
+    if Prelude.null errs
+        then Right lists
+        else Left $ "could not parse line(s) " ++ intercalate ", " (show <$> errs)
+
 
 -- stringify code
 join :: Text -> [Text] -> Text
-join = foldl' Data.Text.append
+join = foldl' T.append
 
 subTaskToString :: MarkdownConfig -> Text -> SubTask -> Text
 subTaskToString config t st = join t [
@@ -77,7 +89,7 @@ taskToString config s t = join s [
 
 listToString :: MarkdownConfig -> Text -> List -> Text
 listToString config s l = join s [
-        if Data.Text.null s then "" else "\n"
+        if T.null s then "" else "\n"
       , titleOutput config
       , " "
       , title l

src/IO/Taskell.hs

@@ -41,7 +41,7 @@ writeFile :: Config -> Lists -> FilePath -> IO ()
 writeFile config tasks path = void (BS.writeFile path $ stringify config tasks)
 
 -- reads json file
-readFile :: Config -> FilePath -> IO Lists
+readFile :: Config -> FilePath -> IO (Either String Lists)
 readFile config path = do
     content <- BS.readFile path
     return $ parse config content