display cmdparamdesc in optparse-applicative usage messages

Since optparse-applicative display "FOO" as "[FOO]", the paramOptional
modifier which wrapped it in square brackets was removed from most places.

CmdLine/Usage.hs

@@ -58,7 +58,7 @@ commandUsage cmd = unlines
 
 {- Descriptions of params used in usage messages. -}
 paramPaths :: String
-paramPaths = paramOptional $ paramRepeating paramPath -- most often used
+paramPaths = paramRepeating paramPath -- most often used
 paramPath :: String
 paramPath = "PATH"
 paramKey :: String
@@ -114,6 +114,6 @@ paramNothing = ""
 paramRepeating :: String -> String
 paramRepeating s = s ++ " ..."
 paramOptional :: String -> String
-paramOptional s = "[" ++ s ++ "]"
+paramOptional s = s
 paramPair :: String -> String -> String
 paramPair a b = a ++ " " ++ b

Command.hs

@@ -36,13 +36,17 @@ import CmdLine.GitAnnex.Options as ReExported
 import qualified Options.Applicative as O
 
 {- Generates a normal Command -}
-command :: String -> String -> CommandSection -> String -> CommandParser -> Command
-command = Command [] Nothing commonChecks False False
+command :: String -> String -> CommandSection -> String -> (Command -> CommandParser) -> Command
+command name paramdesc section desc parser = c
+  where
+	c = Command [] Nothing commonChecks False False name paramdesc section desc (parser c)
 
 {- Simple CommandParser generator, for when the CommandSeek wants all
  - non-option parameters. -}
-commandParser :: (CmdParams -> CommandSeek) -> CommandParser
-commandParser mkseek = mkseek <$> O.many (O.argument O.str O.idm)
+commandParser :: (CmdParams -> CommandSeek) -> Command -> CommandParser
+commandParser mkseek c = mkseek <$> O.many cmdparams
+  where
+	cmdparams = O.argument O.str (O.metavar (cmdparamdesc c))
 
 {- Indicates that a command doesn't need to commit any changes to
  - the git-annex branch. -}

Command/Help.hs

@@ -23,7 +23,7 @@ import System.Console.GetOpt
 
 cmd :: Command
 cmd = noCommit $ noRepo startNoRepo $ dontCheck repoExists $
-	command "help" (paramOptional "COMMAND") seek SectionCommon "display help"
+	command "help" "COMMAND" seek SectionCommon "display help"
 
 seek :: CommandSeek
 seek = withWords start

Command/Info.hs

@@ -80,7 +80,7 @@ type StatState = StateT StatInfo Annex
 
 cmd :: Command
 cmd = noCommit $ dontCheck repoExists $ withOptions (jsonOption : bytesOption : annexedMatchingOptions) $
-	command "info" (paramOptional $ paramRepeating paramItem) seek SectionQuery
+	command "info" (paramRepeating paramItem) seek SectionQuery
 	"shows information about the specified item or the repository as a whole"
 
 seek :: CommandSeek

Command/ReKey.hs

@@ -20,7 +20,7 @@ import qualified Remote
 
 cmd :: Command
 cmd = notDirect $ command "rekey"
-	(paramOptional $ paramRepeating $ paramPair paramPath paramKey)
+	(paramRepeating $ paramPair paramPath paramKey)
 	seek SectionPlumbing "change keys used for files"
 
 seek :: CommandSeek

Command/Sync.hs

@@ -53,7 +53,7 @@ import qualified Data.Map as M
 
 cmd :: Command
 cmd = withOptions syncOptions $
-	command "sync" (paramOptional (paramRepeating paramRemote))
+	command "sync" (paramRepeating paramRemote)
 	seek SectionCommon "synchronize local repository with remotes"
 
 syncOptions :: [Option]

Command/VPop.hs

@@ -18,7 +18,7 @@ import Command.View (checkoutViewBranch)
 
 cmd :: Command
 cmd = notBareRepo $ notDirect $
-	command "vpop" (paramOptional paramNumber) seek SectionMetaData
+	command "vpop" paramNumber seek SectionMetaData
 	"switch back to previous view"
 
 seek :: CommandSeek