diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 `simple-cmd-args` uses [PVP Versioning](https://pvp.haskell.org).
 
+## 0.1.6 (2020-03-25)
+- subcommands now have --help option
+- output a warning if there are duplicate commands
+
 ## 0.1.5 (2020-02-06)
 - add Eq and Ord instances for Subcommand
 
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -14,14 +14,28 @@
 ```haskell
 import SimpleCmdArgs
 import Control.Applicative (some)
-import SimpleCmd (cmd_)
+import System.Directory
 
 main =
-  simpleCmdArgs Nothing "my example tool" "Longer description..." $
+  simpleCmdArgs Nothing "example-tool" "Longer description..." $
   subcommands
-    [ Subcommand "echo" "Print name" $ putStrLn <$> strArg "NAME"
-    , Subcommand "ls" "Touch FILE" $ cmd_ "ls" <$> some (strArg "FILE...")
+    [ Subcommand "echo" "Print words" $
+      putStrLn . unwords <$> some (strArg "STR...")
+    , Subcommand "ls" "List directory" $
+      ls <$> strArg "DIR"
+    , Subcommand "mkdir" "Create directory" $
+      mkdir <$> parentsOpt <*> strArg "DIR"
     ]
+  where
+    parentsOpt = switchWith 'p' "parents" "Make missing directories"
+
+ls :: FilePath -> IO ()
+ls dir =
+  listDirectory dir >>= mapM_ putStrLn
+
+mkdir :: Bool -> FilePath -> IO ()
+mkdir parents =
+  if parents then createDirectoryIfMissing True else createDirectory
 ```
 
 See more [examples](https://github.com/juhp/simple-cmd-args/tree/master/examples).
diff --git a/SimpleCmdArgs.hs b/SimpleCmdArgs.hs
--- a/SimpleCmdArgs.hs
+++ b/SimpleCmdArgs.hs
@@ -10,8 +10,10 @@
   (simpleCmdArgs,
    simpleCmdArgs',
    simpleCmdArgsWithMods,
+   -- * Subcommands
    Subcommand(..),
    subcommands,
+   -- * Option and arg helpers
    strArg,
    switchWith,
    flagWith,
@@ -24,6 +26,7 @@
    optionalWith,
    optionalMods,
    argumentWith,
+   -- * Re-exports from optparse-applicative
    Parser,
    auto,
    many,
@@ -38,19 +41,27 @@
   )
 where
 
+#if (defined(MIN_VERSION_base) && MIN_VERSION_base(4,13,0))
+#else
 import Control.Applicative ((<|>),
 #if (defined(MIN_VERSION_base) && MIN_VERSION_base(4,8,0))
 #else
                             (<$>), (<*>)
 #endif
                            )
+#endif
 import Control.Monad (join)
+import Data.List (nub)
 #if (defined(MIN_VERSION_base) && MIN_VERSION_base(4,8,0))
 #else
 import Data.Monoid (mconcat)
 #endif
+#if (defined(MIN_VERSION_base) && MIN_VERSION_base(4,13,0))
+#else
 import Data.Semigroup ((<>))
+#endif
 import Data.Version
+import Debug.Trace (trace)
 import Options.Applicative
 
 -- | Parser executor (allows interspersed args and options)
@@ -110,20 +121,33 @@
 data Subcommand =
   Subcommand String String (Parser (IO ()))
 
+subCmdName :: Subcommand -> String
+subCmdName (Subcommand n _ _) = n
+
+-- | equality by command name
+--
 -- @since 0.1.5
 instance Eq Subcommand where
-  (Subcommand n1 _ _) == (Subcommand n2 _ _) = n1 == n2
+  c1 == c2 = subCmdName c1 == subCmdName c2
 
+-- | comparison by command name
+--
 -- @since 0.1.5
 instance Ord Subcommand where
-  compare (Subcommand n1 _ _) (Subcommand n2 _ _) = compare n1 n2
+  compare c1 c2 = compare (subCmdName c1) (subCmdName c2)
 
--- | list of @Subcommand@ that can be run by @simpleCmdArgs@
+-- | Create a list of @Subcommand@ that can be run by @simpleCmdArgs@
 subcommands :: [Subcommand] -> Parser (IO ())
-subcommands = subparser . mconcat . map cmdToParse
+subcommands = hsubparser . mconcat . map cmdToParse . warnIfDuplicates
   where
     cmdToParse (Subcommand name cmddesc cmdparse) =
       command name (info cmdparse (progDesc cmddesc))
+
+    warnIfDuplicates :: [Subcommand] -> [Subcommand]
+    warnIfDuplicates subcmds =
+      if dups then trace "duplicate subcommand found" subcmds else subcmds
+      where
+        dups = nub subcmds /= subcmds
 
 -- | A string arg parser with a METAVAR for help
 strArg :: String -> Parser String
diff --git a/simple-cmd-args.cabal b/simple-cmd-args.cabal
--- a/simple-cmd-args.cabal
+++ b/simple-cmd-args.cabal
@@ -1,6 +1,6 @@
 cabal-version:       1.18
 name:                simple-cmd-args
-version:             0.1.5
+version:             0.1.6
 synopsis:            Simple command args parsing and execution
 description:
             This is a small wrapper over optparse-applicative which
@@ -20,7 +20,7 @@
                    , CHANGELOG.md
 tested-with:         GHC == 7.4.2, GHC == 7.6.3, GHC == 7.8.4,
                      GHC == 7.10.3, GHC == 8.0.2, GHC == 8.2.2,
-                     GHC == 8.4.4, GHC == 8.6.5, GHC == 8.8.2
+                     GHC == 8.4.4, GHC == 8.6.5, GHC == 8.8.3
 
 source-repository head
   type:                git