Switch to optparse-applicative

src/Main.hs

@@ -9,41 +9,63 @@ import Data.Aeson                  (decode, toJSON)
 import Data.Maybe                  (fromJust)
 import Data.HashMap.Strict         (delete)
 import Data.ByteString.Lazy.Char8  (pack)
-import System.Console.ArgParser
+import Options.Applicative
 import System.Process
 
-data ProgArgs = ProgArgs
+
+-- * CLI interface
+
+-- | Program arguments record
+data Options = Options
   { name     :: String
   , url      :: String
   , dnschain :: Bool
   , block    :: Bool
   , raw      :: Bool
-  } deriving (Show)
+  }
 
-parser :: ParserSpec ProgArgs
-parser = ProgArgs
-  `parsedBy` reqPos   "name"     `Descr` "Namecoin name id"
-  `andBy`    optFlag  "http://dns.dnschain.net/" "url"
-                                 `Descr` "Use custom api url"
-  `andBy`    boolFlag "dnschain" `Descr` "Use dnschain api"
-  `andBy`    boolFlag "block"    `Descr` "Show blockchain data (require local connecton)"
-  `andBy`    boolFlag "raw"      `Descr` "Print raw JSON data"
+-- | Program arguments parser
+options :: Parser Options
+options = Options
+  <$> strArgument ( help "Namecoin name id" )
+  <*> strOption
+      ( long "url"
+     <> short 'u'
+     <> value "http://dns.dnschain.net/"
+     <> metavar "URL"
+     <> help "Use custom api url" )
+  <*> switch
+      ( long "dnschain"
+     <> short 'd'
+     <> help "Use dnschain api")
+  <*> switch
+      ( long "block"
+     <> short 'b'
+     <> help "Show blockchain data (require local connection)")
+  <*> switch
+      ( long "raw"
+     <> short 'r'
+     <> help "Print raw JSON data")
 
-interface :: IO (CmdLnInterface ProgArgs)
-interface =
-  (`setAppDescr`  "Query the namecoin blockchain") .
-  (`setAppEpilog` "Stat rosa pristina nomine, nomina nuda tenemus.") <$>
-  mkApp parser
 
+-- | Program description
+description :: ParserInfo Options
+description = info (helper <*> options)
+  ( fullDesc
+ <> progDesc "Query the namecoin blockchain"
+ <> footer "Stat rosa pristina nomine, nomina nuda tenemus." )
+
+
+-- | Main function
 main :: IO ()
-main = interface >>= flip runApp exec
+main = execParser description >>= exec where
+  exec Options{..} =
+    if dnschain
+      then doDnschain url name raw
+      else doLocal name block
 
-exec :: ProgArgs -> IO ()
-exec ProgArgs{..} =
-  if dnschain
-  then doDnschain url name raw
-  else doLocal name block
 
+-- | Connect to local namecoin node
 doLocal :: String -> Bool -> IO ()
 doLocal name block = do
   out <- readProcess "namecoin-cli" ["name_show", name] ""
@@ -56,12 +78,14 @@ doLocal name block = do
         reparse = fromJust . decode . pack
         extra   = toJSON (delete "value" res)
 
+
+-- | Connect to dnschain api endpoint
 doDnschain :: String -> String -> Bool -> IO ()
 doDnschain url name raw = do
   body <- (^. responseBody) <$> get (url ++ name)
   if raw
-  then print body
-  else putStrLn $
-    case decode body of
-      Just res -> repr res
-      Nothing  -> "Error parsing data"
+    then print body
+    else putStrLn $
+      case decode body of
+        Just res -> repr res
+        Nothing  -> "Error parsing data"