print hint for non-zero exit code in non-json mode

src/Main.hs

@@ -6,6 +6,7 @@
 
 module Main where
 
+import           Control.Monad            (unless)
 import           Control.Monad.Identity   (Identity)
 import           Data.Aeson               (eitherDecode, encode)
 import           Data.Aeson.Encode.Pretty (encodePretty)
@@ -13,33 +14,33 @@ import           Data.Aeson.KeyMap        (coercionToHashMap)
 import qualified Data.ByteString.Char8    as C8
 import qualified Data.ByteString.Lazy     as LB
 import           Data.Maybe               (fromMaybe)
-import           System.Exit              (exitWith, ExitCode (..))
+import           System.Exit              (ExitCode (..), exitWith)
 import           WithCli
 
 import           CheckDir                 (recursiveCheckDir, resultIsFatal)
-import           LintConfig               (LintConfig (..), patch)
+import           LintConfig               (LintConfig (..), patchConfig)
+import           System.IO                (hPutStrLn, stderr)
 import           Types                    (Level (..))
 import           Util                     (printPretty)
 import           WriteRepo                (writeAdjustedRepository)
-import System.IO (hPutStrLn, stderr)
 
 -- | the options this cli tool can take
 data Options = Options
-  { repository   :: Maybe String
+  { repository :: Maybe String
   -- ^ path to the repository containing maps to lint
-  , entrypoint   :: Maybe String
+  , entrypoint :: Maybe String
   -- ^ entrypoint in that repository
-  , json         :: Bool
+  , json       :: Bool
   -- ^ emit json if --json was given
-  , lintlevel    :: Maybe Level
+  , lintlevel  :: Maybe Level
   -- ^ maximum lint level to print
-  , pretty       :: Bool
+  , pretty     :: Bool
   -- ^ pretty-print the json to make it human-readable
-  , out          :: Maybe String
+  , out        :: Maybe String
   -- ^ path to write the (possibly adjusted) maps to after linting
-  , configFile   :: Maybe FilePath
+  , configFile :: Maybe FilePath
   -- ^ path to a config file. Currently required.
-  , config       :: Maybe (LintConfig Maybe)
+  , config     :: Maybe (LintConfig Maybe)
   -- ^ a "patch" for the configuration file
   } deriving (Show, Generic, HasArguments)
 
@@ -59,10 +60,8 @@ run options = do
     Nothing -> error "Need a config file!"
     Just path -> LB.readFile path >>= \res ->
       case eitherDecode res :: Either String (LintConfig Identity) of
-        Left err -> error $ "config file invalid: " <> err
-        Right file -> case config options of
-          Just p  -> pure (patch file p)
-          Nothing -> pure file
+        Left err   -> error $ "config file invalid: " <> err
+        Right file -> pure (patchConfig file (config options))
 
   lints <- recursiveCheckDir lintconfig repo entry
 
@@ -72,11 +71,20 @@ run options = do
     else printPretty (level, lints)
 
   case out options of
-    Just outpath -> writeAdjustedRepository lintconfig repo outpath lints
-                    >>= exitWith
     Nothing -> exitWith $ case resultIsFatal lintconfig lints of
       False -> ExitSuccess
-      True -> ExitFailure 1
+      True  -> ExitFailure 1
+    Just outpath -> do
+      c <- writeAdjustedRepository lintconfig repo outpath lints
+      unless (json options) $
+        case c of
+          ExitFailure 1 -> putStrLn "\nMap failed linting!"
+          ExitFailure 2 -> putStrLn "\nOutpath already exists, not writing anything."
+          _ -> pure ()
+      exitWith c
+
+
+
 
 -- | haskell's many string types are FUN …
 printLB :: LB.ByteString -> IO ()