Put suggestions into their own ParserHelp record.

This would allow one to either delete them or not
show things like usage if there is a suggestion.

Options/Applicative/Extra.hs

@@ -144,6 +144,7 @@ parserFailure pprefs pinfo msg ctx = ParserFailure $ \progn ->
   let h = with_context ctx pinfo $ \names pinfo' -> mconcat
             [ base_help pinfo'
             , usage_help progn names pinfo'
+            , suggestion_help
             , error_help ]
   in (h, exit_code, prefColumns pprefs)
   where
@@ -185,6 +186,22 @@ parserFailure pprefs pinfo msg ctx = ParserFailure $ \progn ->
       MissingError _ (SomeParser x)
         -> stringChunk "Missing:" <<+>> missingDesc pprefs x
 
+      UnexpectedError arg _
+        -> stringChunk msg'
+          where
+            --
+            -- This gives us the same error we have always
+            -- reported
+            --
+            msg' = case arg of
+              ('-':_) -> "Invalid option `" ++ arg ++ "'"
+              _       -> "Invalid argument `" ++ arg ++ "'"
+
+      UnknownError
+        -> mempty
+
+
+    suggestion_help = suggestionsHelp $ case msg of
       UnexpectedError arg (SomeParser x)
         --
         -- We have an unexpected argument and the parser which
@@ -194,15 +211,8 @@ parserFailure pprefs pinfo msg ctx = ParserFailure $ \progn ->
         -- a levenstein distance between all possible suggestions
         -- and the supplied option or argument.
         --
-        -> vsepChunks [stringChunk msg', suggestions]
+        -> suggestions
           where
-            --
-            -- This gives us the same error we have always
-            -- reported
-            msg' = case arg of
-              ('-':_) -> "Invalid option `" ++ arg ++ "'"
-              _       -> "Invalid argument `" ++ arg ++ "'"
-
             --
             -- Not using chunked here, as we don't want to
             -- show "Did you mean" if there's nothing there
@@ -219,12 +229,12 @@ parserFailure pprefs pinfo msg ctx = ParserFailure $ \progn ->
             --
             -- Suggestions we will show, they're close enough
             -- to what the user wrote
-            good        = filter (isClose arg) possibles
+            good        = filter isClose possibles
 
             --
             -- Bit of an arbitrary decision here.
             -- Edit distances of 1 or 2 will give hints
-            isClose a b = editDistance a b < 3
+            isClose a   = editDistance a arg < 3
 
             --
             -- Similar to how bash completion works.
@@ -250,7 +260,7 @@ parserFailure pprefs pinfo msg ctx = ParserFailure $ \progn ->
             show_name (OptShort c) = '-':[c]
             show_name (OptLong l) = "--" ++ l
 
-      UnknownError
+      _
         -> mempty
 
     base_help :: ParserInfo a -> ParserHelp

Options/Applicative/Help/Core.hs

@@ -7,6 +7,7 @@ module Options.Applicative.Help.Core (
   ParserHelp(..),
   errorHelp,
   headerHelp,
+  suggestionsHelp,
   usageHelp,
   bodyHelp,
   footerHelp,
@@ -131,19 +132,22 @@ fullDesc pprefs = tabulate . catMaybes . mapParser doc
       , descSurround = False }
 
 errorHelp :: Chunk Doc -> ParserHelp
-errorHelp chunk = ParserHelp chunk mempty mempty mempty mempty
+errorHelp chunk = mempty { helpError = chunk }
 
 headerHelp :: Chunk Doc -> ParserHelp
-headerHelp chunk = ParserHelp mempty chunk mempty mempty mempty
+headerHelp chunk = mempty { helpHeader = chunk }
+
+suggestionsHelp :: Chunk Doc -> ParserHelp
+suggestionsHelp chunk = mempty { helpSuggestions = chunk }
 
 usageHelp :: Chunk Doc -> ParserHelp
-usageHelp chunk = ParserHelp mempty mempty chunk mempty mempty
+usageHelp chunk = mempty { helpUsage = chunk }
 
 bodyHelp :: Chunk Doc -> ParserHelp
-bodyHelp chunk = ParserHelp mempty mempty mempty chunk mempty
+bodyHelp chunk = mempty { helpBody = chunk }
 
 footerHelp :: Chunk Doc -> ParserHelp
-footerHelp chunk = ParserHelp mempty mempty mempty mempty chunk
+footerHelp chunk = mempty { helpFooter = chunk }
 
 -- | Generate the help text for a program.
 parserHelp :: ParserPrefs -> Parser a -> ParserHelp

Options/Applicative/Help/Types.hs

@@ -1,6 +1,6 @@
 module Options.Applicative.Help.Types (
-  ParserHelp(..),
-  renderHelp
+    ParserHelp (..)
+  , renderHelp
   ) where
 
 import Data.Semigroup
@@ -11,6 +11,7 @@ import Options.Applicative.Help.Pretty
 
 data ParserHelp = ParserHelp
   { helpError :: Chunk Doc
+  , helpSuggestions :: Chunk Doc
   , helpHeader :: Chunk Doc
   , helpUsage :: Chunk Doc
   , helpBody :: Chunk Doc
@@ -20,17 +21,17 @@ instance Show ParserHelp where
   showsPrec _ h = showString (renderHelp 80 h)
 
 instance Monoid ParserHelp where
-  mempty = ParserHelp mempty mempty mempty mempty mempty
+  mempty = ParserHelp mempty mempty mempty mempty mempty mempty
   mappend = (<>)
 
 instance Semigroup ParserHelp where
-  (ParserHelp e1 h1 u1 b1 f1) <> (ParserHelp e2 h2 u2 b2 f2)
-    = ParserHelp (mappend e1 e2) (mappend h1 h2)
-                 (mappend u1 u2) (mappend b1 b2)
-                 (mappend f1 f2)
+  (ParserHelp e1 s1 h1 u1 b1 f1) <> (ParserHelp e2 s2 h2 u2 b2 f2)
+    = ParserHelp (mappend e1 e2) (mappend s1 s2)
+                 (mappend h1 h2) (mappend u1 u2)
+                 (mappend b1 b2) (mappend f1 f2)
 
 helpText :: ParserHelp -> Doc
-helpText (ParserHelp e h u b f) = extractChunk . vsepChunks $ [e, h, u, b, f]
+helpText (ParserHelp e s h u b f) = extractChunk . vsepChunks $ [e, s, h, u, b, f]
 
 -- | Convert a help text to 'String'.
 renderHelp :: Int -> ParserHelp -> String

tests/commands_header.err.txt

@@ -1,3 +1,6 @@
-Invalid option `-zzz'
+Invalid option `-zello'
+
+Did you mean this?
+    hello
 
 Usage: commands_header COMMAND

tests/commands_header_full.err.txt

@@ -1,4 +1,7 @@
-Invalid option `-zzz'
+Invalid option `-zello'
+
+Did you mean this?
+    hello
 
 foo
 

tests/test.hs

@@ -74,9 +74,9 @@ prop_cmd_header :: Property
 prop_cmd_header = once $
   let i  = info (helper <*> Commands.sample) (header "foo")
       r1 = checkHelpTextWith (ExitFailure 1) defaultPrefs
-                    "commands_header" i ["-zzz"]
+                    "commands_header" i ["-zello"]
       r2 = checkHelpTextWith (ExitFailure 1) (prefs showHelpOnError)
-                    "commands_header_full" i ["-zzz"]
+                    "commands_header_full" i ["-zello"]
   in  (r1 .&&. r2)
 
 prop_cabal_conf :: Property
@@ -549,7 +549,7 @@ prop_suggest = once $
   in assertError result $ \failure ->
     let (msg, _)  = renderFailure failure "prog"
     in  counterexample msg
-       $  isInfixOf "Did you mean this?\n    reachable\n" msg
+       $  isInfixOf "Did you mean this?\n    reachable" msg
       .&. not (isInfixOf "unreachable" msg)
 
 ---