Show help for root command with -h, --help, help

Add same for version

src/CliSpec.purs

@@ -65,17 +65,31 @@ callCommand (CliSpec cliSpec) usageString args executor = do
       setExitCode 1
       pure (Error "No arguments provided")
 
-    Just _mainCmd -> do
+    Just firstArg | firstArg == FlagShort 'h'
+                    ||  firstArg == FlagLong "help"
+                    ||  firstArg == CmdArg "help" -> do
+                          log usageString
+                          pure $ Ok unit
+
+    Just firstArg | firstArg == FlagShort 'v'
+                    ||  firstArg == FlagLong "version"
+                    ||  firstArg == CmdArg "version" -> do
+                          log usageString
+                          pure $ Ok unit
+
+    Just _mainCmd ->
       case args # drop 1 # head of
         Just arg | arg == (CmdArg "help")
                     || arg == (FlagLong "help")
                     || arg == (FlagShort 'h') -> do
+                        -- TODO: Only show help for subcommand
                         log usageString
                         pure $ Ok unit
 
         Just arg | arg == (CmdArg "version")
                     || arg == (FlagLong "version")
                     || arg == (FlagShort 'v') -> do
+                        -- TODO: Only show version of subcommand (if available)
                         log (cliSpec.version # fromMaybe "0")
                         pure $ Ok unit
 

src/CliSpec/Parser.purs

@@ -130,10 +130,17 @@ tokensToCliArguments cliSpec@(CliSpec cliSpecRaw) tokens = do
             "Something went wrong. "
             <> "The first token should be a command or a value."
 
-
-  -- If the first token after the main command is a subcommand
-  -- parse recursively the rest of the tokens.
   case tokens # drop 1 # head of
+    Just (FlagShortToken 'h') -> Ok [FlagShort 'h']
+    Just (FlagLongToken "help") -> Ok [FlagLong "help"]
+    Just (TextToken "help") -> Ok [CmdArg "help"]
+
+    Just (FlagShortToken 'v') -> Ok [FlagShort 'v']
+    Just (FlagLongToken "version") -> Ok [FlagLong "version"]
+    Just (TextToken "version") -> Ok [CmdArg "version"]
+
+    -- | If first token after the main command is a subcommand
+    -- | recursively parse the rest of the tokens.
     Just (TextToken name) ->
       case findSubCmd cliSpecRaw.commands name of
         -- Is subcommand

test/CliSpec.purs

@@ -302,6 +302,93 @@ tests = do
               ]
 
     describe "Execution" do
+      describe "Help" do
+        let
+          cliSpec = CliSpec emptyCliSpecRaw
+          usageString = "Irrelevant"
+          executor cmdName usageStr providedArgs = do
+            cmdName `shouldEqual` "help"
+            usageStr `shouldEqual` usageString
+            providedArgs `shouldEqual` []
+            pure $ Ok unit
+
+        it "shows help output for -h" do
+          let
+            toolArgs = ["git", "-h"]
+            tokens = tokenizeCliArguments toolArgs
+
+          case tokensToCliArguments cliSpec tokens of
+            Error err -> fail err
+            Ok cliArgs ->
+              liftEffect (callCommand cliSpec usageString cliArgs executor)
+                `shouldReturn` (Ok unit)
+
+        it "shows help output for --help" do
+          let
+            toolArgs = ["git", "--help"]
+            tokens = tokenizeCliArguments toolArgs
+
+          case tokensToCliArguments cliSpec tokens of
+            Error err -> fail err
+            Ok cliArgs ->
+              liftEffect (callCommand cliSpec usageString cliArgs executor)
+                `shouldReturn` (Ok unit)
+
+        it "shows help output for `help`" do
+          let
+            toolArgs = ["git", "help"]
+            tokens = tokenizeCliArguments toolArgs
+
+          case tokensToCliArguments cliSpec tokens of
+            Error err -> fail err
+            Ok cliArgs ->
+              liftEffect (callCommand cliSpec usageString cliArgs executor)
+                `shouldReturn` (Ok unit)
+
+      describe "Version" do
+        let
+          cliSpec = CliSpec emptyCliSpecRaw
+          usageString = "Irrelevant"
+          executor cmdName usageStr providedArgs = do
+            cmdName `shouldEqual` "help"
+            usageStr `shouldEqual` usageString
+            providedArgs `shouldEqual` []
+            pure $ Ok unit
+
+        it "shows help output for -v" do
+          let
+            toolArgs = ["git", "-v"]
+            tokens = tokenizeCliArguments toolArgs
+
+          case tokensToCliArguments cliSpec tokens of
+            Error err -> fail err
+            Ok cliArgs ->
+              liftEffect (callCommand cliSpec usageString cliArgs executor)
+                `shouldReturn` (Ok unit)
+
+        it "shows help output for --version" do
+          let
+            toolArgs = ["git", "--version"]
+            tokens = tokenizeCliArguments toolArgs
+
+          case tokensToCliArguments cliSpec tokens of
+            Error err -> fail err
+            Ok cliArgs ->
+              liftEffect (callCommand cliSpec usageString cliArgs executor)
+                `shouldReturn` (Ok unit)
+
+        it "shows help output for `help`" do
+          let
+            toolArgs = ["git", "help"]
+            tokens = tokenizeCliArguments toolArgs
+
+          case tokensToCliArguments cliSpec tokens of
+            Error err -> fail err
+            Ok cliArgs ->
+              liftEffect (callCommand cliSpec usageString cliArgs executor)
+                `shouldReturn` (Ok unit)
+
+
       it "executes a sub-command with one argument" do
         let
           cliSpec = CliSpec (emptyCliSpecRaw
@@ -378,12 +465,8 @@ tests = do
         case (tokensToCliArguments cliSpec $ tokenizeCliArguments args) of
           Error err -> fail err
           Ok cliArgs ->
-              liftEffect (callCommand
-                cliSpec
-                usageString
-                cliArgs
-                executor
-              ) `shouldReturn` (Ok unit)
+              liftEffect (callCommand cliSpec usageString cliArgs executor)
+                `shouldReturn` (Ok unit)
 
       it "executes a sub-command with one option" do
         let