Add back positional argument parsers and short names

src/Turtle/Options.hs

@@ -9,8 +9,8 @@
 -- > import Turtle
 -- >
 -- > parser :: Parser (Text, Int)
--- > parser = (,) <$> argText     "name" "Your first name"
--- >              <*> argIntegral "age"  "Your current age"
+-- > parser = (,) <$> optText     "name" "Your first name"
+-- >              <*> optIntegral "age"  "Your current age"
 -- >
 -- > main = do
 -- >     (name, age) <- options "Greeting script" parser
@@ -24,7 +24,7 @@
 -- > $ ./options --help
 -- > Greeting script
 -- >
--- > Usage: options --name NAME --age AGE
+-- > Usage: options (-n|--name NAME) (-a|--age AGE)
 -- >
 -- > Available options:
 -- >  -h,--help                Show this help text
@@ -38,8 +38,15 @@ module Turtle.Options
     , Description
     , HelpMessage
 
-      -- * Build parsers
+      -- * Flag-based option parsers
     , switch
+    , optText
+    , optIntegral
+    , optFractional
+    , optRead
+    , opt
+
+    -- * Positional argument parsers
     , argText
     , argIntegral
     , argFractional
@@ -73,9 +80,9 @@ options desc parser = liftIO
 
 {-| The name of a command-line argument
 
-    This is used to infer the long name and metavariable for the command line
-    flag.  For example, an `ArgName` of @\"name\"@ will create a @--name@ flag
-    with a @NAME@ metavariable
+    This is used to infer the long name, short name, and metavariable for the
+    command line flag.  For example, an `ArgName` of @\"name\"@ will create a
+    @--name@ flag with a @NAME@ metavariable and a short name of @-n@
 -}
 newtype ArgName = ArgName { getArgName :: Text }
     deriving (IsString)
@@ -104,37 +111,74 @@ switch
 switch argName helpMessage
    = Opts.switch
    $ (Opts.long . Text.unpack . getArgName) argName
+  <> foldMap (Opts.short . fst) (Text.uncons (getArgName argName))
   <> foldMap (Opts.help . Text.unpack . getHelpMessage) helpMessage
 
-{- | Build an argument parser for any type by providing a `Text`-parsing
+{- | Build a flag-based option parser for any type by providing a `Text`-parsing
      function
 -}
+opt :: (Text -> Maybe a)
+    -> ArgName
+    -> Optional HelpMessage
+    -> Parser a
+opt argParse argName helpMessage
+   = Opts.option (argParseToReadM argParse)
+   $ Opts.metavar (Text.unpack (Text.toUpper (getArgName argName)))
+  <> Opts.long (Text.unpack (getArgName argName))
+  <> foldMap (Opts.short . fst) (Text.uncons (getArgName argName))
+  <> foldMap (Opts.help . Text.unpack . getHelpMessage) helpMessage
+
+-- | Parse any type that implements `Read`
+optRead :: Read a => ArgName -> Optional HelpMessage -> Parser a
+optRead = opt (readMaybe . Text.unpack)
+
+{-| Parse any type that implements `Integral` as n flag-based option
+
+    This is most commonly used to parse an `Int` or `Integer`
+-}
+optIntegral :: Integral n => ArgName -> Optional HelpMessage -> Parser n
+optIntegral argName helpMessage = fmap fromInteger (optRead argName helpMessage)
+
+-- | Parse a `Text` value as a flag-based option
+optText :: ArgName -> Optional HelpMessage -> Parser Text
+optText = opt Just
+
+{-| Parse any type that implements `Fractional` as a flag-based option
+
+    This is most commonly used to parse a `Double`
+-}
+optFractional :: Fractional n => ArgName -> Optional HelpMessage -> Parser n
+optFractional argName helpMessage =
+    fmap fromRational (optRead argName helpMessage)
+
+{- | Build a positional argument parser for any type by providing a
+    `Text`-parsing function
+-}
 arg :: (Text -> Maybe a)
     -> ArgName
     -> Optional HelpMessage
     -> Parser a
 arg argParse argName helpMessage
-   = Opts.option (argParseToReadM argParse)
+   = Opts.argument (argParseToReadM argParse)
    $ Opts.metavar (Text.unpack (Text.toUpper (getArgName argName)))
-  <> Opts.long (Text.unpack (getArgName argName))
   <> foldMap (Opts.help . Text.unpack . getHelpMessage) helpMessage
 
--- | Parse any type that implements `Read`
+-- | Parse any type that implements `Read` as a positional argument
 argRead :: Read a => ArgName -> Optional HelpMessage -> Parser a
 argRead = arg (readMaybe . Text.unpack)
 
-{-| Parse any type that implements `Integral`
+{-| Parse any type that implements `Integral` as a positional argument
 
     This is most commonly used to parse an `Int` or `Integer`
 -}
 argIntegral :: Integral n => ArgName -> Optional HelpMessage -> Parser n
 argIntegral argName helpMessage = fmap fromInteger (argRead argName helpMessage)
 
--- | Parse a `Text` value
+-- | Parse a `Text` value as a positional argument
 argText :: ArgName -> Optional HelpMessage -> Parser Text
 argText = arg Just
 
-{-| Parse any type that implements `Fractional`
+{-| Parse any type that implements `Fractional` as a positional argument
 
     This is most commonly used to parse a `Double`
 -}