separating flags into separate module

IHaskell.cabal

@@ -95,6 +95,7 @@ library
                    IHaskell.Eval.ParseShell
                    IHaskell.Eval.Util
                    IHaskell.IPython
+                   IHaskell.Flags
                    IHaskell.Message.Parser
                    IHaskell.Message.UUID
                    IHaskell.Message.Writer
@@ -121,6 +122,7 @@ executable IHaskell
              IHaskell.Eval.ParseShell
              IHaskell.Eval.Util
              IHaskell.IPython
+             IHaskell.Flags
              IHaskell.Message.Parser
              IHaskell.Message.UUID
              IHaskell.Message.Writer

src/IHaskell/Flags.hs

+{-# LANGUAGE NoImplicitPrelude #-}
+module IHaskell.Flags ( 
+  IHaskellMode(..),
+  Argument(..),
+  Args(..),
+  parseFlags,
+  help,
+  ) where
+
+import ClassyPrelude
+import System.Console.CmdArgs.Explicit
+import System.Console.CmdArgs.Text
+
+import IHaskell.Types
+
+-- Command line arguments to IHaskell.  A set of aruments is annotated with
+-- the mode being invoked.
+data Args = Args IHaskellMode [Argument]
+
+data Argument
+  = ServeFrom String    -- ^ Which directory to serve notebooks from.
+  | Extension String    -- ^ An extension to load at startup.
+  | ConfFile String     -- ^ A file with commands to load at startup.
+  | Help                -- ^ Display help text.
+  deriving (Eq, Show)
+
+-- Which mode IHaskell is being invoked in.
+-- `None` means no mode was specified.
+data IHaskellMode
+  = ShowHelp String
+  | Notebook
+  | Console
+  | UpdateIPython
+  | Kernel (Maybe String)
+  | View (Maybe ViewFormat) (Maybe String)
+  deriving (Eq, Show)
+
+-- | Given a list of command-line arguments, return the IHaskell mode and
+-- arguments to process.
+parseFlags :: [String] -> Either String Args
+parseFlags = process ihaskellArgs
+
+-- | Get help text for a given IHaskell ode.
+help :: IHaskellMode -> String
+help mode = 
+    showText (Wrap 100) $ helpText [] HelpFormatAll $ chooseMode mode
+  where
+    chooseMode Console = console
+    chooseMode Notebook = notebook
+    chooseMode (Kernel _) = kernel
+    chooseMode UpdateIPython = update
+
+universalFlags :: [Flag Args]
+universalFlags = [
+  flagReq ["extension","e", "X"] (store Extension) "<ghc-extension>" "Extension to enable at start.",
+  flagReq ["conf","c"] (store ConfFile) "<file.hs>" "File with commands to execute at start.",
+  flagHelpSimple (add Help)
+  ]
+  where 
+    add flag (Args mode flags) = Args mode $ flag : flags
+
+store :: (String -> Argument) -> String -> Args -> Either String Args
+store constructor str (Args mode prev) = Right $ Args mode $ constructor str : prev
+
+notebook :: Mode Args
+notebook = mode "notebook" (Args Notebook []) "Browser-based notebook interface." noArgs $
+  flagReq ["serve","s"] (store ServeFrom) "<dir>" "Directory to serve notebooks from.":
+  universalFlags
+
+console :: Mode Args
+console = mode "console" (Args Console []) "Console-based interactive repl." noArgs universalFlags
+
+kernel = mode "kernel" (Args (Kernel Nothing) []) "Invoke the IHaskell kernel." kernelArg []
+  where
+    kernelArg = flagArg update "<json-kernel-file>"
+    update filename (Args _ flags) = Right $ Args (Kernel $ Just filename) flags
+
+update :: Mode Args
+update = mode "update" (Args UpdateIPython []) "Update IPython frontends." noArgs []
+
+view :: Mode Args
+view = (modeEmpty $ Args (View Nothing Nothing) []) {
+      modeNames = ["view"],
+      modeCheck  =
+        \a@(Args (View fmt file) _) ->
+          if not (isJust fmt && isJust file)
+          then Left "Syntax: IHaskell view <format> <name>[.ipynb]"
+          else Right a,
+      modeHelp = concat [
+        "Convert an IHaskell notebook to another format.\n",
+        "Notebooks are searched in the IHaskell directory and the current directory.\n",
+        "Available formats are " ++ intercalate ", " (map show 
+          ["pdf", "html", "ipynb", "markdown", "latex"]),
+        "."
+      ],
+      modeArgs = ([formatArg, filenameArg], Nothing)
+                                                    
+  }
+  where
+    formatArg = flagArg updateFmt "<format>"
+    filenameArg = flagArg updateFile "<name>[.ipynb]"
+    updateFmt fmtStr (Args (View _ s) flags) = 
+      case readMay fmtStr of
+        Just fmt -> Right $ Args (View (Just fmt) s) flags
+        Nothing -> Left $ "Invalid format '" ++ fmtStr ++ "'."
+    updateFile name (Args (View f _) flags) = Right $ Args (View f (Just name)) flags
+  
+
+ihaskellArgs :: Mode Args
+ihaskellArgs =
+  let descr = "Haskell for Interactive Computing." 
+      helpStr = showText (Wrap 100) $ helpText [] HelpFormatAll ihaskellArgs
+      onlyHelp = [flagHelpSimple (add Help)]
+      noMode = mode "IHaskell" (Args (ShowHelp helpStr) []) descr noArgs onlyHelp in
+    noMode { modeGroupModes = toGroup [console, notebook, view, update, kernel] }
+  where 
+    add flag (Args mode flags) = Args mode $ flag : flags
+
+noArgs = flagArg unexpected ""
+  where
+    unexpected a = error $ "Unexpected argument: " ++ a

src/IHaskell/IPython.hs

@@ -26,44 +26,12 @@ import Data.List.Utils (split)
 import Data.String.Utils (rstrip)
 import Text.Printf
 
-import Text.Read as Read hiding (pfail)
-import Text.ParserCombinators.ReadP
-
 import qualified System.IO.Strict as StrictIO
 import qualified Paths_ihaskell as Paths
 import qualified Codec.Archive.Tar as Tar
 
 import IHaskell.Types
 
-data ViewFormat
-     = Pdf
-     | Html
-     | Ipynb
-     | Markdown
-     | Latex
-     deriving Eq
-
-instance Show ViewFormat where
-  show Pdf         = "pdf"
-  show Html        = "html"
-  show Ipynb       = "ipynb"
-  show Markdown    = "markdown"
-  show Latex       = "latex"
-
-instance Read ViewFormat where
-  readPrec = Read.lift $ do
-    str <- munch (const True)
-    case str of
-      "pdf" -> return Pdf
-      "html" -> return Html
-      "ipynb" -> return Ipynb
-      "notebook" -> return Ipynb
-      "latex" -> return Latex
-      "markdown" -> return Markdown
-      "md" -> return Markdown
-      _ -> pfail
-
-
 -- | Which commit of IPython we are on.
 ipythonCommit :: Text
 ipythonCommit = "9c922f54af799704f4000aeee94ec7c74cada194"

src/IHaskell/Types.hs

@@ -21,6 +21,7 @@ module IHaskell.Types (
   LintStatus(..),
   Width, Height,
   FrontendType(..),
+  ViewFormat(..),
   defaultKernelState,
   extractPlain
   ) where
@@ -32,6 +33,37 @@ import Data.Serialize
 import GHC.Generics (Generic)
 import qualified Data.ByteString.Char8 as Char
 
+import Text.Read as Read hiding (pfail, String)
+import Text.ParserCombinators.ReadP
+
+data ViewFormat
+     = Pdf
+     | Html
+     | Ipynb
+     | Markdown
+     | Latex
+     deriving Eq
+
+instance Show ViewFormat where
+  show Pdf         = "pdf"
+  show Html        = "html"
+  show Ipynb       = "ipynb"
+  show Markdown    = "markdown"
+  show Latex       = "latex"
+
+instance Read ViewFormat where
+  readPrec = Read.lift $ do
+    str <- munch (const True)
+    case str of
+      "pdf" -> return Pdf
+      "html" -> return Html
+      "ipynb" -> return Ipynb
+      "notebook" -> return Ipynb
+      "latex" -> return Latex
+      "markdown" -> return Markdown
+      "md" -> return Markdown
+      _ -> pfail
+
 
 -- | A TCP port.
 type Port = Int

src/Main.hs

@@ -12,7 +12,6 @@ import Data.Aeson
 import Text.Printf
 import System.Exit (exitSuccess)
 import System.Directory
-import System.Console.CmdArgs.Explicit hiding (complete)
 
 import qualified Data.Map as Map
 
@@ -25,113 +24,25 @@ import IHaskell.Eval.Info
 import qualified Data.ByteString.Char8 as Chars
 import IHaskell.IPython
 import qualified IHaskell.Eval.Stdin as Stdin
+import IHaskell.Flags
 
 import GHC hiding (extensions)
 import Outputable (showSDoc, ppr)
 
--- Command line arguments to IHaskell.  A set of aruments is annotated with
--- the mode being invoked.
-data Args = Args IHaskellMode [Argument]
-
-data Argument
-  = ServeFrom String    -- ^ Which directory to serve notebooks from.
-  | Extension String    -- ^ An extension to load at startup.
-  | ConfFile String     -- ^ A file with commands to load at startup.
-  | Help                -- ^ Display help text.
-  deriving (Eq, Show)
-
--- Which mode IHaskell is being invoked in.
--- `None` means no mode was specified.
-data IHaskellMode
-  = None
-  | Notebook
-  | Console
-  | UpdateIPython
-  | Kernel (Maybe String)
-  | View (Maybe ViewFormat) (Maybe String)
-  deriving (Eq, Show)
 
 main ::  IO ()
 main = do
-  stringArgs <- map unpack <$> getArgs
-  case process ihaskellArgs stringArgs of
-    Left errmsg -> putStrLn $ pack errmsg
+  args <- parseFlags <$> map unpack <$> getArgs
+  case args of
+    Left errorMessage -> 
+      hPutStrLn stderr errorMessage
     Right args ->
       ihaskell args
 
-universalFlags :: [Flag Args]
-universalFlags = [
-  flagReq ["extension","e", "X"] (store Extension) "<ghc-extension>" "Extension to enable at start.",
-  flagReq ["conf","c"] (store ConfFile) "<file.hs>" "File with commands to execute at start.",
-  flagHelpSimple (add Help)
-  ]
-  where 
-    add flag (Args mode flags) = Args mode $ flag : flags
-
-store :: (String -> Argument) -> String -> Args -> Either String Args
-store constructor str (Args mode prev) = Right $ Args mode $ constructor str : prev
-
-notebook :: Mode Args
-notebook = mode "notebook" (Args Notebook []) "Browser-based notebook interface." noArgs $
-  flagReq ["serve","s"] (store ServeFrom) "<dir>" "Directory to serve notebooks from.":
-  universalFlags
-
-console :: Mode Args
-console = mode "console" (Args Console []) "Console-based interactive repl." noArgs universalFlags
-
-kernel = mode "kernel" (Args (Kernel Nothing) []) "Invoke the IHaskell kernel." kernelArg []
-  where
-    kernelArg = flagArg update "<json-kernel-file>"
-    update filename (Args _ flags) = Right $ Args (Kernel $ Just filename) flags
-
-update :: Mode Args
-update = mode "update" (Args UpdateIPython []) "Update IPython frontends." noArgs []
-
-view :: Mode Args
-view = (modeEmpty $ Args (View Nothing Nothing) []) {
-      modeNames = ["view"],
-      modeCheck  =
-        \a@(Args (View fmt file) _) ->
-          if not (isJust fmt && isJust file)
-          then Left "Syntax: IHaskell view <format> <name>[.ipynb]"
-          else Right a,
-      modeHelp = concat [
-        "Convert an IHaskell notebook to another format.\n",
-        "Notebooks are searched in the IHaskell directory and the current directory.\n",
-        "Available formats are " ++ intercalate ", " (map show 
-          ["pdf", "html", "ipynb", "markdown", "latex"]),
-        "."
-      ],
-      modeArgs = ([formatArg, filenameArg], Nothing)
-                                                    
-  }
-  where
-    formatArg = flagArg updateFmt "<format>"
-    filenameArg = flagArg updateFile "<name>[.ipynb]"
-    updateFmt fmtStr (Args (View _ s) flags) = 
-      case readMay fmtStr of
-        Just fmt -> Right $ Args (View (Just fmt) s) flags
-        Nothing -> Left $ "Invalid format '" ++ fmtStr ++ "'."
-    updateFile name (Args (View f _) flags) = Right $ Args (View f (Just name)) flags
-  
-
-ihaskellArgs :: Mode Args
-ihaskellArgs =
-  let descr = "Haskell for Interactive Computing." 
-      onlyHelp = [flagHelpSimple (add Help)]
-      noMode = mode "IHaskell" (Args None []) descr noArgs onlyHelp in
-    noMode { modeGroupModes = toGroup [console, notebook, view, update, kernel] }
-  where 
-    add flag (Args mode flags) = Args mode $ flag : flags
-
-noArgs = flagArg unexpected ""
-  where
-    unexpected a = error $ "Unexpected argument: " ++ a
-
 ihaskell :: Args -> IO ()
 -- If no mode is specified, print help text.
-ihaskell (Args None _) = 
-  print $ helpText [] HelpFormatAll ihaskellArgs
+ihaskell (Args (ShowHelp help) _) = 
+  putStrLn $ pack help
 
 -- Update IPython: remove then reinstall.
 -- This is in case cabal updates IHaskell but the corresponding IPython
@@ -188,14 +99,9 @@ showingHelp :: IHaskellMode -> [Argument] -> IO () -> IO ()
 showingHelp mode flags act =
   case find (==Help) flags of
     Just _ ->
-      print $ helpText [] HelpFormatAll $ chooseMode mode
+      putStrLn $ pack $ help mode
     Nothing ->
       act
-  where
-    chooseMode Console = console
-    chooseMode Notebook = notebook
-    chooseMode (Kernel _) = kernel
-    chooseMode UpdateIPython = update
  
 -- | Parse initialization information from the flags.
 initInfo :: FrontendType -> [Argument] -> IO InitInfo