Add basic version parser.

Adds a simple expansion of infoOption both for documentation
and the basic use case.

src/Options/Applicative.hs

@@ -74,6 +74,7 @@ module Options.Applicative (
   abortOption,
   infoOption,
   helper,
+  simpleVersioner,
 
   -- ** Modifiers
   --

src/Options/Applicative/Extra.hs

@@ -6,6 +6,7 @@ module Options.Applicative.Extra (
   helper,
   helperWith,
   hsubparser,
+  simpleVersioner,
   execParser,
   customExecParser,
   execParserPure,
@@ -93,6 +94,19 @@ hsubparser m = mkParser d g rdr
     add_helper pinfo = pinfo
       { infoParser = infoParser pinfo <**> helper }
 
+-- | A hidden \"--version\" option that displays the version.
+--
+-- > opts :: ParserInfo Sample
+-- > opts = info (sample <**> simpleVersioner "v1.2.3") mempty
+simpleVersioner :: String -- ^ Version string to be shown
+                -> Parser (a -> a)
+simpleVersioner version = infoOption version $
+  mconcat
+    [ long "version"
+    , help "Show version information"
+    , hidden
+    ]
+
 -- | Run a program description.
 --
 -- Parse command line arguments. Display help text and exit if any parse error

tests/Examples/Cabal.hs

@@ -39,10 +39,6 @@ data BuildOpts = BuildOpts
   { buildDir :: FilePath }
   deriving Show
 
-version :: Parser (a -> a)
-version = infoOption "0.0.0"
-  (  long "version"
-  <> help "Print version information" )
 
 parser :: Parser Args
 parser = runA $ proc () -> do
@@ -60,7 +56,7 @@ parser = runA $ proc () -> do
            <> command "build"
               (info buildParser
                     (progDesc "Make this package ready for installation")) ) -< ()
-  A version >>> A helper -< Args opts cmds
+  A (simpleVersioner "0.0.0") >>> A helper -< Args opts cmds
 
 commonOpts :: Parser CommonOpts
 commonOpts = CommonOpts

tests/cabal.err.txt

@@ -9,4 +9,4 @@ Available options:
 
 Global options:
   -v,--verbose LEVEL       Set verbosity to LEVEL
-  --version                Print version information
+  --version                Show version information