Add support for labeled module references

doc/markup.rst

@@ -982,6 +982,11 @@ is valid before turning it into a link but unlike with identifiers,
 whether the module is in scope isn't checked and will always be turned
 into a link.
 
+It is also possible to specify alternate text for the generated link
+using syntax analogous to that used for URLs: ::
+
+  -- | This is a reference to [the main module]("Module.Main").
+
 Itemized and Enumerated Lists
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

haddock-api/src/Haddock/Backends/Hoogle.hs

@@ -325,7 +325,7 @@ markupTag dflags = Markup {
   markupAppend               = (++),
   markupIdentifier           = box (TagInline "a") . str . out dflags,
   markupIdentifierUnchecked  = box (TagInline "a") . str . showWrapped (out dflags . snd),
-  markupModule               = box (TagInline "a") . str,
+  markupModule               = \(ModLink m label) -> box (TagInline "a") (fromMaybe (str m) label),
   markupWarning              = box (TagInline "i"),
   markupEmphasis             = box (TagInline "i"),
   markupBold                 = box (TagInline "b"),

haddock-api/src/Haddock/Backends/LaTeX.hs

@@ -1210,7 +1210,12 @@ latexMarkup = Markup
   , markupAppend               = \l r v -> l v . r v
   , markupIdentifier           = \i v -> inlineElem (markupId v (fmap occName i))
   , markupIdentifierUnchecked  = \i v -> inlineElem (markupId v (fmap snd i))
-  , markupModule               = \m _ -> inlineElem (let (mdl,_ref) = break (=='#') m in (tt (text mdl)))
+  , markupModule               =
+      \(ModLink m mLabel) v ->
+        case mLabel of
+          Just lbl -> inlineElem . tt $ lbl v empty
+          Nothing -> inlineElem (let (mdl,_ref) = break (=='#') m
+                                 in (tt (text mdl)))
   , markupWarning              = \p v -> p v
   , markupEmphasis             = \p v -> inlineElem (emph (p v empty))
   , markupBold                 = \p v -> inlineElem (bold (p v empty))

haddock-api/src/Haddock/Backends/Xhtml/DocMarkup.hs

@@ -44,13 +44,14 @@ parHtmlMarkup qual insertAnchors ppId = Markup {
   markupAppend               = (+++),
   markupIdentifier           = thecode . ppId insertAnchors,
   markupIdentifierUnchecked  = thecode . ppUncheckedLink qual,
-  markupModule               = \m -> let (mdl,ref) = break (=='#') m
-                                         -- Accomodate for old style
-                                         -- foo\#bar anchors
-                                         mdl' = case reverse mdl of
-                                           '\\':_ -> init mdl
-                                           _ -> mdl
-                                     in ppModuleRef (mkModuleName mdl') ref,
+  markupModule               = \(ModLink m lbl) ->
+                                 let (mdl,ref) = break (=='#') m
+                                       -- Accomodate for old style
+                                       -- foo\#bar anchors
+                                     mdl' = case reverse mdl of
+                                              '\\':_ -> init mdl
+                                              _ -> mdl
+                                 in ppModuleRef lbl (mkModuleName mdl') ref,
   markupWarning              = thediv ! [theclass "warning"],
   markupEmphasis             = emphasize,
   markupBold                 = strong,

haddock-api/src/Haddock/Backends/Xhtml/Names.hs

@@ -186,9 +186,12 @@ ppModule mdl = anchor ! [href (moduleUrl mdl)]
                << toHtml (moduleString mdl)
 
 
-ppModuleRef :: ModuleName -> String -> Html
-ppModuleRef mdl ref = anchor ! [href (moduleHtmlFile' mdl ++ ref)]
-                      << toHtml (moduleNameString mdl)
+ppModuleRef :: Maybe Html -> ModuleName -> String -> Html
+ppModuleRef Nothing mdl ref = anchor ! [href (moduleHtmlFile' mdl ++ ref)]
+                              << toHtml (moduleNameString mdl)
+ppModuleRef (Just lbl) mdl ref = anchor ! [href (moduleHtmlFile' mdl ++ ref)]
+                                 << lbl
+
     -- NB: The ref parameter already includes the '#'.
     -- This function is only called from markupModule expanding a
     -- DocModule, which doesn't seem to be ever be used.

haddock-api/src/Haddock/Interface/Json.hs

@@ -98,9 +98,9 @@ jsonDoc (DocIdentifierUnchecked modName) = jsonObject
     , ("modName", jsonString (showModName modName))
     ]
 
-jsonDoc (DocModule s) = jsonObject
+jsonDoc (DocModule (ModLink m _l)) = jsonObject
     [ ("tag", jsonString "DocModule")
-    , ("string", jsonString s)
+    , ("string", jsonString m)
     ]
 
 jsonDoc (DocWarning x) = jsonObject

haddock-api/src/Haddock/Interface/LexParseRn.hs

@@ -148,7 +148,7 @@ rename dflags gre = rn
       DocDefList list -> DocDefList <$> traverse (\(a, b) -> (,) <$> rn a <*> rn b) list
       DocCodeBlock doc -> DocCodeBlock <$> rn doc
       DocIdentifierUnchecked x -> pure (DocIdentifierUnchecked x)
-      DocModule str -> pure (DocModule str)
+      DocModule (ModLink m l) -> DocModule . ModLink m <$> traverse rn l
       DocHyperlink (Hyperlink u l) -> DocHyperlink . Hyperlink u <$> traverse rn l
       DocPic str -> pure (DocPic str)
       DocMathInline str -> pure (DocMathInline str)

haddock-api/src/Haddock/InterfaceFile.hs

@@ -84,7 +84,7 @@ binaryInterfaceMagic = 0xD0Cface
 --
 binaryInterfaceVersion :: Word16
 #if MIN_VERSION_ghc(9,0,0) && !MIN_VERSION_ghc(9,1,0)
-binaryInterfaceVersion = 37
+binaryInterfaceVersion = 38
 
 binaryInterfaceVersionCompatibility :: [Word16]
 binaryInterfaceVersionCompatibility = [binaryInterfaceVersion]
@@ -444,6 +444,15 @@ instance Binary a => Binary (Hyperlink a) where
         label <- get bh
         return (Hyperlink url label)
 
+instance Binary a => Binary (ModLink a) where
+    put_ bh (ModLink m label) = do
+        put_ bh m
+        put_ bh label
+    get bh = do
+        m <- get bh
+        label <- get bh
+        return (ModLink m label)
+
 instance Binary Picture where
     put_ bh (Picture uri title) = do
         put_ bh uri

haddock-api/src/Haddock/Types.hs

@@ -501,6 +501,9 @@ instance NFData id => NFData (Header id) where
 instance NFData id => NFData (Hyperlink id) where
   rnf (Hyperlink a b) = a `deepseq` b `deepseq` ()
 
+instance NFData id => NFData (ModLink id) where
+  rnf (ModLink a b) = a `deepseq` b `deepseq` ()
+
 instance NFData Picture where
   rnf (Picture a b) = a `deepseq` b `deepseq` ()
 

haddock-library/fixtures/Fixtures.hs

@@ -149,6 +149,9 @@ instance ToExpr id => ToExpr (Header id)
 deriving instance Generic (Hyperlink id)
 instance ToExpr id => ToExpr (Hyperlink id)
 
+deriving instance Generic (ModLink id)
+instance ToExpr id => ToExpr (ModLink id)
+
 deriving instance Generic Picture
 instance ToExpr Picture
 

haddock-library/src/Documentation/Haddock/Markup.hs

@@ -16,7 +16,7 @@ markup m (DocString s)                  = markupString m s
 markup m (DocParagraph d)               = markupParagraph m (markup m d)
 markup m (DocIdentifier x)              = markupIdentifier m x
 markup m (DocIdentifierUnchecked x)     = markupIdentifierUnchecked m x
-markup m (DocModule mod0)               = markupModule m mod0
+markup m (DocModule (ModLink mo l))     = markupModule m (ModLink mo (fmap (markup m) l))
 markup m (DocWarning d)                 = markupWarning m (markup m d)
 markup m (DocEmphasis d)                = markupEmphasis m (markup m d)
 markup m (DocBold d)                    = markupBold m (markup m d)
@@ -78,7 +78,7 @@ plainMarkup plainMod plainIdent = Markup {
   markupAppend               = (++),
   markupIdentifier           = plainIdent,
   markupIdentifierUnchecked  = plainMod,
-  markupModule               = id,
+  markupModule               = \(ModLink m lbl) -> fromMaybe m lbl,
   markupWarning              = id,
   markupEmphasis             = id,
   markupBold                 = id,

haddock-library/src/Documentation/Haddock/Parser.hs

@@ -72,7 +72,7 @@ overIdentifier f d = g d
     g (DocString x) = DocString x
     g (DocParagraph x) = DocParagraph $ g x
     g (DocIdentifierUnchecked x) = DocIdentifierUnchecked x
-    g (DocModule x) = DocModule x
+    g (DocModule (ModLink m x)) = DocModule (ModLink m (fmap g x))
     g (DocWarning x) = DocWarning $ g x
     g (DocEmphasis x) = DocEmphasis $ g x
     g (DocMonospaced x) = DocMonospaced $ g x
@@ -148,6 +148,7 @@ parseParagraph = snd . parse p
                                     , mathDisplay
                                     , mathInline
                                     , markdownImage
+                                    , markdownLink
                                     , hyperlink
                                     , bold
                                     , emphasis
@@ -242,21 +243,43 @@ monospace = DocMonospaced . parseParagraph
 -- Note that we allow '#' and '\' to support anchors (old style anchors are of
 -- the form "SomeModule\#anchor").
 moduleName :: Parser (DocH mod a)
-moduleName = DocModule <$> ("\"" *> (modid `maybeFollowedBy` anchor_) <* "\"")
+moduleName = DocModule . flip ModLink Nothing <$> ("\"" *> moduleNameString <* "\"")
+
+-- | A module name, optionally with an anchor
+--
+moduleNameString :: Parser String
+moduleNameString = modid `maybeFollowedBy` anchor_
   where
     modid = intercalate "." <$> conid `Parsec.sepBy1` "."
     anchor_ = (++)
       <$> (Parsec.string "#" <|> Parsec.string "\\#")
       <*> many (Parsec.satisfy (\c -> c /= '"' && not (isSpace c)))
 
     maybeFollowedBy pre suf = (\x -> maybe x (x ++)) <$> pre <*> optional suf
-
+    conid :: Parser String
     conid = (:)
       <$> Parsec.satisfy (\c -> isAlpha c && isUpper c)
       <*> many conChar
 
     conChar = Parsec.alphaNum <|> Parsec.char '_'
 
+-- | A labeled link to an indentifier, module or url using markdown
+-- syntax.
+markdownLink :: Parser (DocH mod Identifier)
+markdownLink = do
+  lbl <- markdownLinkText
+  choice' [ markdownModuleName lbl, markdownURL lbl ]
+  where
+    markdownModuleName lbl = do
+      mn <- "(" *> skipHorizontalSpace *>
+            "\"" *> moduleNameString <* "\""
+            <* skipHorizontalSpace <* ")"
+      pure $ DocModule (ModLink mn (Just lbl))
+
+    markdownURL lbl = do
+      target <- markdownLinkTarget
+      pure $ DocHyperlink $ Hyperlink target (Just lbl)
+
 -- | Picture parser, surrounded by \<\< and \>\>. It's possible to specify
 -- a title for the picture.
 --
@@ -290,9 +313,11 @@ mathDisplay = DocMathDisplay . T.unpack
 -- >>> parseString "![some /emphasis/ in a description](www.site.com)"
 -- DocPic (Picture "www.site.com" (Just "some emphasis in a description"))
 markdownImage :: Parser (DocH mod Identifier)
-markdownImage = DocPic . fromHyperlink <$> ("!" *> linkParser)
+markdownImage = do
+  text <- markup stringMarkup <$> ("!" *> markdownLinkText)
+  url <- markdownLinkTarget
+  pure $ DocPic (Picture url (Just text))
   where
-    fromHyperlink (Hyperlink u l) = Picture u (fmap (markup stringMarkup) l)
     stringMarkup = plainMarkup (const "") renderIdent
     renderIdent (Identifier ns l c r) = renderNs ns <> [l] <> c <> [r]
 
@@ -772,22 +797,21 @@ codeblock =
           | otherwise = Just $ c == '\n'
 
 hyperlink :: Parser (DocH mod Identifier)
-hyperlink = choice' [ angleBracketLink, markdownLink, autoUrl ]
+hyperlink = choice' [ angleBracketLink, autoUrl ]
 
 angleBracketLink :: Parser (DocH mod a)
 angleBracketLink =
     DocHyperlink . makeLabeled (\s -> Hyperlink s . fmap DocString)
     <$> disallowNewline ("<" *> takeUntil ">")
 
-markdownLink :: Parser (DocH mod Identifier)
-markdownLink = DocHyperlink <$> linkParser
+-- | The text for a markdown link, enclosed in square brackets.
+markdownLinkText :: Parser (DocH mod Identifier)
+markdownLinkText = parseParagraph . T.strip <$> ("[" *> takeUntil "]")
 
-linkParser :: Parser (Hyperlink (DocH mod Identifier))
-linkParser = flip Hyperlink <$> label <*> (whitespace *> url)
+-- | The target for a markdown link, enclosed in parenthesis.
+markdownLinkTarget :: Parser String
+markdownLinkTarget = whitespace *> url
   where
-    label :: Parser (Maybe (DocH mod Identifier))
-    label = Just . parseParagraph . T.strip <$> ("[" *> takeUntil "]")
-
     whitespace :: Parser ()
     whitespace = skipHorizontalSpace <* optional ("\n" *> skipHorizontalSpace)
 

haddock-library/src/Documentation/Haddock/Types.hs

@@ -73,6 +73,11 @@ data Hyperlink id = Hyperlink
   , hyperlinkLabel :: Maybe id
   } deriving (Eq, Show, Functor, Foldable, Traversable)
 
+data ModLink id = ModLink
+  { modLinkName   :: String
+  , modLinkLabel :: Maybe id
+  } deriving (Eq, Show, Functor, Foldable, Traversable)
+
 data Picture = Picture
   { pictureUri   :: String
   , pictureTitle :: Maybe String
@@ -111,7 +116,8 @@ data DocH mod id
   | DocIdentifier id
   | DocIdentifierUnchecked mod
   -- ^ A qualified identifier that couldn't be resolved.
-  | DocModule String
+  | DocModule (ModLink (DocH mod id))
+  -- ^ A link to a module, with an optional label.
   | DocWarning (DocH mod id)
   -- ^ This constructor has no counterpart in Haddock markup.
   | DocEmphasis (DocH mod id)
@@ -142,7 +148,7 @@ instance Bifunctor DocH where
   bimap f g (DocParagraph doc) = DocParagraph (bimap f g doc)
   bimap _ g (DocIdentifier i) = DocIdentifier (g i)
   bimap f _ (DocIdentifierUnchecked m) = DocIdentifierUnchecked (f m)
-  bimap _ _ (DocModule s) = DocModule s
+  bimap f g (DocModule (ModLink m lbl)) = DocModule (ModLink m (fmap (bimap f g) lbl))
   bimap f g (DocWarning doc) = DocWarning (bimap f g doc)
   bimap f g (DocEmphasis doc) = DocEmphasis (bimap f g doc)
   bimap f g (DocMonospaced doc) = DocMonospaced (bimap f g doc)
@@ -189,7 +195,7 @@ instance Bitraversable DocH where
   bitraverse f g (DocParagraph doc) = DocParagraph <$> bitraverse f g doc
   bitraverse _ g (DocIdentifier i) = DocIdentifier <$> g i
   bitraverse f _ (DocIdentifierUnchecked m) = DocIdentifierUnchecked <$> f m
-  bitraverse _ _ (DocModule s) = pure (DocModule s)
+  bitraverse f g (DocModule (ModLink m lbl)) = DocModule <$> (ModLink m <$> traverse (bitraverse f g) lbl)
   bitraverse f g (DocWarning doc) = DocWarning <$> bitraverse f g doc
   bitraverse f g (DocEmphasis doc) = DocEmphasis <$> bitraverse f g doc
   bitraverse f g (DocMonospaced doc) = DocMonospaced <$> bitraverse f g doc
@@ -234,7 +240,7 @@ data DocMarkupH mod id a = Markup
   , markupAppend               :: a -> a -> a
   , markupIdentifier           :: id -> a
   , markupIdentifierUnchecked  :: mod -> a
-  , markupModule               :: String -> a
+  , markupModule               :: ModLink a -> a
   , markupWarning              :: a -> a
   , markupEmphasis             :: a -> a
   , markupBold                 :: a -> a