Better error messages for transformation config loading

src-extra/transformation/JbeamEdit/Transformation/Config.hs

@@ -16,7 +16,13 @@ module JbeamEdit.Transformation.Config (
 
 import Data.Scientific (Scientific)
 import Data.Text qualified as T
-import Data.Yaml (decodeFileEither)
+import Data.Yaml (
+  Object,
+  ParseException (..),
+  Parser,
+  decodeFileEither,
+  prettyPrintParseException,
+ )
 import Data.Yaml.Aeson (
   FromJSON (..),
   withArray,
@@ -107,25 +113,28 @@ instance FromJSON XGroupBreakpoints where
         obj
     pure $ XGroupBreakpoints lst
 
+parseSupportThreshold :: Object -> Parser Double
+parseSupportThreshold o = do
+  thr <- o .: "support-threshold"
+  when (thr < 1) failWithMessage $> thr
+  where
+    failWithMessage =
+      fail
+        "'support-threshold' must be a percentage value of 1 or higher (e.g., 80 or 80.8). Values below 1 (e.g., 0.80) are not allowed."
+
 instance FromJSON TransformationConfig where
   parseJSON = withObject "TransformationConfig" $ \o ->
     TransformationConfig
       <$> o .:? "z-sorting-threshold" .!= defaultSortingThreshold
       <*> o .:? "x-group-breakpoints" .!= defaultBreakpoints
-      <*> o .:? "support-threshold" .!= defaultSupportThreshold
+      <*> parseSupportThreshold o
       <*> o .:? "max-support-coordinates" .!= defaultMaxSupportCoordinates
 
+formatParseError :: ParseException -> IO ()
+formatParseError (AesonException err) = putErrorStringLn err
+formatParseError excp = putErrorStringLn (prettyPrintParseException excp)
+
 loadTransformationConfig :: FilePath -> IO TransformationConfig
 loadTransformationConfig filename = do
   res <- decodeFileEither filename
-  case res of
-    Right tc -> pure tc
-    Left err -> do
-      putErrorLine $ show err
-      pure
-        ( TransformationConfig
-            defaultSortingThreshold
-            defaultBreakpoints
-            defaultSupportThreshold
-            defaultMaxSupportCoordinates
-        )
+  either ((newTransformationConfig <$) . formatParseError) pure res

src/JbeamEdit/Formatting/Config.hs

@@ -2,7 +2,6 @@
 
 module JbeamEdit.Formatting.Config (readFormattingConfig, copyToConfigDir, ConfigType (..)) where
 
-import Data.Text (pack)
 import GHC.IO.Exception (IOErrorType (NoSuchThing))
 import JbeamEdit.Formatting.Rules
 import JbeamEdit.IOUtils
@@ -71,7 +70,7 @@ readFormattingConfig maybeJbflPath = do
   configDir <- getConfigDir
   case maybeJbflPath of
     Just jbfl ->
-      putErrorLine $ "Loading jbfl: " <> pack jbfl
+      putErrorStringLn $ "Loading jbfl: " ++ jbfl
     Nothing ->
       createRuleFileIfDoesNotExist (configDir </> "rules.jbfl")
   configPath <- getConfigPath maybeJbflPath configDir

src/JbeamEdit/IOUtils.hs

@@ -1,4 +1,4 @@
-module JbeamEdit.IOUtils (tryReadFile, putErrorLine, reportInvalidNodes) where
+module JbeamEdit.IOUtils (tryReadFile, putErrorLine, putErrorStringLn, reportInvalidNodes) where
 
 import Control.Exception (IOException, try)
 import Control.Monad (unless)
@@ -13,8 +13,11 @@ import JbeamEdit.Core.Node (Node)
 import JbeamEdit.Formatting (formatNode, newRuleSet)
 import System.IO (hPutStrLn, stderr)
 
+putErrorStringLn :: String -> IO ()
+putErrorStringLn = hPutStrLn stderr
+
 putErrorLine :: Text -> IO ()
-putErrorLine = hPutStrLn stderr . T.unpack
+putErrorLine = putErrorStringLn . T.unpack
 
 reportInvalidNodes :: Text -> [Node] -> IO ()
 reportInvalidNodes msg nodes =