From 7aa84dc168556f65b09d2b0b0281bc9404155145 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roman=20Smr=C5=BE?= <roman.smrz@seznam.cz>
Date: Wed, 29 May 2024 20:43:05 +0200
Subject: Show usage info only with explicit `--help' option

---
 src/Main.hs | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/src/Main.hs b/src/Main.hs
index 318c36f..363fad8 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -20,17 +20,22 @@ import Job
 import Version
 
 data CmdlineOptions = CmdlineOptions
-    { optShowVersion :: Bool
+    { optShowHelp :: Bool
+    , optShowVersion :: Bool
     }
 
 defaultCmdlineOptions :: CmdlineOptions
 defaultCmdlineOptions = CmdlineOptions
-    { optShowVersion = False
+    { optShowHelp = False
+    , optShowVersion = False
     }
 
 options :: [OptDescr (CmdlineOptions -> CmdlineOptions)]
 options =
-    [ Option ['V'] ["version"]
+    [ Option ['h'] ["help"]
+        (NoArg $ \opts -> opts { optShowHelp = True })
+        "show this help and exit"
+    , Option ['V'] ["version"]
         (NoArg $ \opts -> opts { optShowVersion = True })
         "show version and exit"
     ]
@@ -81,8 +86,14 @@ main = do
     args <- getArgs
     opts <- case getOpt Permute options args of
         (o, _, []) -> return (foldl (flip id) defaultCmdlineOptions o)
-        (_, _, errs) -> ioError (userError (concat errs ++ usageInfo header options))
-            where header = "Usage: minici [OPTION...]"
+        (_, _, errs) -> do
+            hPutStrLn stderr $ concat errs <> "Try `minici --help' for more information."
+            exitFailure
+
+    when (optShowHelp opts) $ do
+        let header = "Usage: minici [<option>...]"
+        putStr $ usageInfo header options
+        exitSuccess
 
     when (optShowVersion opts) $ do
         putStrLn versionLine
-- 
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