Updated options module

Changed arg/opt parsing to return monomorphic values and made short name
argument mandatory

src/Turtle/Options.hs

@@ -9,8 +9,8 @@
 -- > import Turtle
 -- >
 -- > parser :: Parser (Text, Int)
--- > parser = (,) <$> optText     "name" "Your first name"
--- >              <*> optIntegral "age"  "Your current age"
+-- > parser = (,) <$> optText "name" 'n' "Your first name"
+-- >              <*> optInt  "age"  'a' "Your current age"
 -- >
 -- > main = do
 -- >     (name, age) <- options "Greeting script" parser
@@ -41,15 +41,17 @@ module Turtle.Options
       -- * Flag-based option parsers
     , switch
     , optText
-    , optIntegral
-    , optFractional
+    , optInt
+    , optInteger
+    , optDouble
     , optRead
     , opt
 
     -- * Positional argument parsers
     , argText
-    , argIntegral
-    , argFractional
+    , argInt
+    , argInteger
+    , argDouble
     , argRead
     , arg
 
@@ -106,12 +108,13 @@ newtype HelpMessage = HelpMessage { getHelpMessage :: Text }
 -}
 switch
     :: ArgName
+    -> Char
     -> Optional HelpMessage
     -> Parser Bool
-switch argName helpMessage
+switch argName c helpMessage
    = Opts.switch
    $ (Opts.long . Text.unpack . getArgName) argName
-  <> foldMap (Opts.short . fst) (Text.uncons (getArgName argName))
+  <> Opts.short c
   <> foldMap (Opts.help . Text.unpack . getHelpMessage) helpMessage
 
 {- | Build a flag-based option parser for any type by providing a `Text`-parsing
@@ -119,38 +122,36 @@ switch argName helpMessage
 -}
 opt :: (Text -> Maybe a)
     -> ArgName
+    -> Char
     -> Optional HelpMessage
     -> Parser a
-opt argParse argName helpMessage
+opt argParse argName c 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))
+  <> Opts.short c
   <> foldMap (Opts.help . Text.unpack . getHelpMessage) helpMessage
 
 -- | Parse any type that implements `Read`
-optRead :: Read a => ArgName -> Optional HelpMessage -> Parser a
+optRead :: Read a => ArgName -> Char -> Optional HelpMessage -> Parser a
 optRead = opt (readMaybe . Text.unpack)
 
-{-| Parse any type that implements `Integral` as n flag-based option
+-- | Parse an `Int` as a flag-based option
+optInt :: ArgName -> Char -> Optional HelpMessage -> Parser Int
+optInt = optRead
 
-    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 an `Integer` as a flag-based option
+optInteger :: ArgName -> Char -> Optional HelpMessage -> Parser Integer
+optInteger = optRead
+
+-- | Parse a `Double` as a flag-based option
+optDouble :: ArgName -> Char -> Optional HelpMessage -> Parser Double
+optDouble = optRead
 
 -- | Parse a `Text` value as a flag-based option
-optText :: ArgName -> Optional HelpMessage -> Parser Text
+optText :: ArgName -> Char -> 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
 -}
@@ -167,25 +168,22 @@ arg argParse argName helpMessage
 argRead :: Read a => ArgName -> Optional HelpMessage -> Parser a
 argRead = arg (readMaybe . Text.unpack)
 
-{-| Parse any type that implements `Integral` as a positional argument
+-- | Parse an `Int` as a positional argument
+argInt :: ArgName -> Optional HelpMessage -> Parser Int
+argInt = argRead
 
-    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 an `Integer` as a positional argument
+argInteger :: ArgName -> Optional HelpMessage -> Parser Integer
+argInteger = argRead
 
--- | Parse a `Text` value as a positional argument
+-- | Parse a `Double` as a positional argument
+argDouble :: ArgName -> Optional HelpMessage -> Parser Double
+argDouble = argRead
+
+-- | Parse a `Text` as a positional argument
 argText :: ArgName -> Optional HelpMessage -> Parser Text
 argText = arg Just
 
-{-| Parse any type that implements `Fractional` as a positional argument
-
-    This is most commonly used to parse a `Double`
--}
-argFractional :: Fractional n => ArgName -> Optional HelpMessage -> Parser n
-argFractional argName helpMessage =
-    fmap fromRational (argRead argName helpMessage)
-
 argParseToReadM :: (Text -> Maybe a) -> Opts.ReadM a
 argParseToReadM f = do
     s <- Opts.readerAsk