Lua: add function `pandoc.utils.documentation` (#11383)

Closes #10999.

This is now used to generate much of the Lua API documentation.

8 files changed, 320 insertions, 73 deletions

diff --git a/doc/lua-filters.md b/doc/lua-filters.md
index 2c82447f9..39e5988fc 100644
--- a/doc/lua-filters.md
+++ b/doc/lua-filters.md
@@ -4163,7 +4163,7 @@ Parameters:
 
 Returns:
 
--  ([Inlines])
+- ([Inlines])
 
 *Since: 2.2.3*
 
@@ -4193,6 +4193,24 @@ Returns:
 
 *Since: 2.19.1*
 
+### documentation {#pandoc.utils.documentation}
+
+`documentation (object[, format])`
+
+Parameters:
+
+`object`
+:   Retrieve documentation for this object (any)
+
+`format`
+:   result format (string\|table)
+
+Returns:
+
+- rendered documentation (string\|[Blocks])
+
+*Since: 3.8.4*
+
 ### equals {#pandoc.utils.equals}
 
 `equals (element1, element2)`
@@ -4207,10 +4225,10 @@ operator instead.
 Parameters:
 
 `element1`
-:    (any)
+:   (any)
 
 `element2`
-:    (any)
+:   (any)
 
 Returns:
 
@@ -4237,7 +4255,7 @@ Usage:
 Parameters:
 
 `simple_tbl`
-:    ([SimpleTable])
+:   ([SimpleTable])
 
 Returns:
 
@@ -4264,8 +4282,7 @@ Parameters:
     attribute containing the section number. (boolean)
 
 `baselevel`
-:   shift top-level headings to this level
-    ([integer]{unknown-type="integer"}\|nil)
+:   shift top-level headings to this level (integer\|nil)
 
 `blocks`
 :   list of blocks to process ([Blocks])
@@ -4292,8 +4309,7 @@ Parameters:
 
 Returns:
 
-- normalized date, or nil if normalization failed. ([string or
-  nil]{unknown-type="string or nil"})
+- normalized date, or nil if normalization failed. (string\|nil)
 
 *Since: 2.0.6*
 
@@ -4389,7 +4405,7 @@ Computes the SHA1 hash of the given string input.
 Parameters:
 
 `input`
-:    (string)
+:   (string)
 
 Returns:
 
@@ -4407,8 +4423,8 @@ string with all formatting removed.
 Parameters:
 
 `element`
-:   some pandoc AST element ([AST
-    element]{unknown-type="AST element"})
+:   some pandoc AST element
+    ([Pandoc]\|[Block]\|[Inline]\|[Caption]\|[Cell]\|[MetaValue])
 
 Returns:
 
@@ -4431,8 +4447,7 @@ Usage:
 Parameters:
 
 `n`
-:   positive integer below 4000
-    ([integer]{unknown-type="integer"})
+:   positive integer below 4000 (integer)
 
 Returns:
 
@@ -4509,8 +4524,8 @@ Creates a Version object.
 Parameters:
 
 `v`
-:   version description ([version string, list of integers, or
-    integer]{unknown-type="version string, list of integers, or integer"})
+:   version description
+    ([Version]\|string\|{integer,\...}\|number)
 
 Returns:
 
@@ -4583,6 +4598,7 @@ Returns:
 
 - The entry's MIME type, or `nil` if the file was not found.
   (string)
+
 - Contents of the file, or `nil` if the file was not found.
   (string)
 
@@ -4630,7 +4646,8 @@ Parameters:
 :   filename and path relative to the output folder. (string)
 
 `mimetype`
-:   the item's MIME type; omit if unknown or unavailable. (string)
+:   the item's MIME type; use `nil` if the MIME type is unknown or
+    unavailable. (string\|nil)
 
 `contents`
 :   the binary contents of the file. (string)
@@ -4714,6 +4731,7 @@ Returns:
 
 - The entry's MIME type, or nil if the file was not found.
   (string)
+
 - Contents of the file, or nil if the file was not found. (string)
 
 *Since: 2.0*
@@ -5044,8 +5062,7 @@ Parameters:
 
 Returns:
 
-- all extensions supported for `format`
-  ([FormatExtensions]{unknown-type="FormatExtensions"})
+- all extensions supported for `format` ([FormatExtensions])
 
 *Since: 3.0*
 
@@ -5064,8 +5081,7 @@ Parameters:
 
 Returns:
 
-- default extensions enabled for `format`
-  ([FormatExtensions]{unknown-type="FormatExtensions"})
+- default extensions enabled for `format` ([FormatExtensions])
 
 *Since: 3.0*
 
@@ -5516,6 +5532,7 @@ Parameters:
 Returns:
 
 - filepath without extension (string)
+
 - extension or empty string (string)
 
 *Since: 2.12*
@@ -5616,7 +5633,7 @@ Parameters:
 
 Returns:
 
-- slide level ([integer]{unknown-type="integer"})
+- slide level (integer)
 
 *Since: 3.0*
 
@@ -5665,7 +5682,7 @@ Parameters:
 
 Returns:
 
--  ([ChunkedDoc])
+- ([ChunkedDoc])
 
 *Since: 3.0*
 
@@ -5765,7 +5782,7 @@ versions and on different platforms.
 
 Returns:
 
-- CPU time in picoseconds ([integer]{unknown-type="integer"})
+- CPU time in picoseconds (integer)
 
 *Since: 3.1.1*
 
@@ -5793,8 +5810,10 @@ Parameters:
 Returns:
 
 - exit code -- `false` on success, an integer otherwise
-  ([integer]{unknown-type="integer"}\|boolean)
+  (integer\|boolean)
+
 - stdout (string)
+
 - stderr (string)
 
 *Since: 3.7.1*
@@ -5971,6 +5990,7 @@ Parameters:
 Returns:
 
 - time at which the file or directory was last modified (table)
+
 - time at which the file or directory was last accessed (table)
 
 *Since: 3.7.1*
@@ -6106,7 +6126,10 @@ Returns:
 <!-- END: AUTOGENERATED CONTENT -->
 
 
-<!-- BEGIN: AUTOGENERATED CONTENT for module pandoc.layout -->
+<!-- Auto-generation temporarily disabled; needs updates in the documenation
+renderer and in `hslua-packaging`. -->
+
+<!-- BEGIN DISABLED: AUTOGENERATED CONTENT for module pandoc.layout -->
 
 # Module pandoc.layout
 
@@ -6822,6 +6845,7 @@ Scaffolding for custom writers.
 An object to be used as a `Writer` function; the construct handles
 most of the boilerplate, expecting only render functions for all
 AST elements (table)
+
 <!-- END: AUTOGENERATED CONTENT -->
 
 <!-- BEGIN: AUTOGENERATED CONTENT for module pandoc.text -->
@@ -6885,7 +6909,7 @@ Parameters:
 
 Returns:
 
-- length ([integer]{unknown-type="integer"}\|string)
+- length (integer\|string)
 
 *Since: 2.0.3*
 
@@ -6936,10 +6960,10 @@ Parameters:
 :   UTF-8 string (string)
 
 `i`
-:   substring start position ([integer]{unknown-type="integer"})
+:   substring start position (integer)
 
 `j`
-:   substring end position ([integer]{unknown-type="integer"})
+:   substring end position (integer)
 
 Returns:
 
@@ -7165,7 +7189,7 @@ Returns:
 
 ## Types {#pandoc.template-types}
 
-### Template {#type-pandoc.Template}
+### Template {#type-pandoc.template.Template}
 
 <!-- END: AUTOGENERATED CONTENT -->
 
@@ -7186,7 +7210,7 @@ Parameters:
 `version_specifier`
 :   A version string like `'2.7.3'`, a Lua number like `2.0`, a
     list of integers like `{2,7,3}`, or a Version object.
-    (string\|number\|{[integer]{unknown-type="integer"},\...}\|[Version])
+    (string\|number\|{integer,\...}\|[Version])
 
 Returns:
 
@@ -7196,7 +7220,9 @@ Returns:
 
 <!-- END: AUTOGENERATED CONTENT -->
 
-<!-- BEGIN: AUTOGENERATED CONTENT for module pandoc.zip -->
+<!-- Disabled due to limitations in the current documentation
+     renderer. -->
+<!-- BEGIN DISABLED: AUTOGENERATED CONTENT for module pandoc.zip -->
 
 # Module pandoc.zip
 
@@ -7255,7 +7281,7 @@ Parameters:
 :   uncompressed contents (string)
 
 `modtime`
-:   modification time ([integer]{unknown-type="integer"})
+:   modification time (integer)
 
 Returns:
 
@@ -7272,7 +7298,7 @@ Generates a ZipEntry from a file or directory.
 Parameters:
 
 `filepath`
-:    (string)
+:   (string)
 
 `opts`
 :   zip options (table)
@@ -7399,7 +7425,9 @@ Returns:
 
 - link target if entry represents a symbolic link (string\|nil)
 
-<!-- END: AUTOGENERATED CONTENT -->
+[zip.Entry]: #type-pandoc.zip.Entry
+[zip.Archive]: #type-pandoc.zip.Archive
+<!-- END DISABLED: AUTOGENERATED CONTENT -->
 
 <!-- BEGIN: GENERATED REFERENCE LINKS -->
 
@@ -7428,6 +7456,7 @@ Returns:
   [Table]: #type-table
   [Version]: #type-version
   [`list`]: #pandoc.mediabag.list
+  [FormatExtensions]: #FormatExtensions
   [WriterOptions]: #type-writeroptions
   [null]: #pandoc.json.null
   [this blog post]: http://neilmitchell.blogspot.co.uk/2015/10/filepaths-are-subtle-symlinks-are-hard.html
@@ -7435,5 +7464,3 @@ Returns:
   [XDG Base Directory Specification]: https://specifications.freedesktop.org/basedir-spec/latest/
   [Doc]: #type-doc
   [Template]: #type-template
-  [zip.Entry]: #type-pandoc.zip.Entry
-  [zip.Archive]: #type-pandoc.zip.Archive
diff --git a/pandoc-lua-engine/pandoc-lua-engine.cabal b/pandoc-lua-engine/pandoc-lua-engine.cabal
index 1086c2db8..cb35943f6 100644
--- a/pandoc-lua-engine/pandoc-lua-engine.cabal
+++ b/pandoc-lua-engine/pandoc-lua-engine.cabal
@@ -69,6 +69,7 @@ library
   hs-source-dirs:      src
   exposed-modules:     Text.Pandoc.Lua
   other-modules:       Text.Pandoc.Lua.Custom
+                     , Text.Pandoc.Lua.Documentation
                      , Text.Pandoc.Lua.Engine
                      , Text.Pandoc.Lua.Filter
                      , Text.Pandoc.Lua.Global
diff --git a/pandoc-lua-engine/src/Text/Pandoc/Lua/Documentation.hs b/pandoc-lua-engine/src/Text/Pandoc/Lua/Documentation.hs
new file mode 100644
index 000000000..833d57603
--- /dev/null
+++ b/pandoc-lua-engine/src/Text/Pandoc/Lua/Documentation.hs
@@ -0,0 +1,187 @@
+{-# LANGUAGE LambdaCase        #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RankNTypes        #-}
+{- |
+   Module      : Text.Pandoc.Lua.Documentation
+   Copyright   : Copyright © 2026 Albert Krewinkel
+   License     : GPL-2.0-or-later
+   Maintainer  : Albert Krewinkel <[email protected]>
+
+Render Lua documentation
+-}
+module Text.Pandoc.Lua.Documentation
+  ( renderDocumentation
+  ) where
+
+import Data.Default (def)
+import Data.List (intersperse)
+import Data.Sequence (Seq ((:|>)))
+import Data.Version (showVersion)
+import HsLua as Lua
+import Text.Pandoc.Class (runPure)
+import Text.Pandoc.Definition (Pandoc (Pandoc))
+import Text.Pandoc.Extensions (extensionsFromList, Extension (..))
+import Text.Pandoc.Options (ReaderOptions (readerExtensions))
+import Text.Pandoc.Readers (readCommonMark)
+import Text.Pandoc.Shared (compactify)
+import Text.Pandoc.Walk (walk)
+
+import qualified Data.Text as T
+import qualified Text.Pandoc.Builder as B
+import qualified Text.Pandoc.UTF8 as UTF8
+
+-- | Render the documentation object as pandoc Blocks
+renderDocumentation :: DocumentationObject -> B.Blocks
+renderDocumentation = \case
+  DocObjectFunction fn -> renderFunctionDoc Nothing fn
+  DocObjectModule mdl  -> renderModuleDoc mdl
+  DocObjectType tp     -> renderTypeDoc Nothing tp
+
+renderTypeDoc :: Maybe T.Text -> TypeDoc -> B.Blocks
+renderTypeDoc mbmodname td = mconcat
+  [ B.headerWith (ident, [], []) 1 (B.str $ typeDocName td)
+  , parseCommonMark $ typeDocDescription td
+  , if null $ typeDocMethods td
+    then mempty
+    else
+      B.header 2 "Methods" <>
+      (shiftHeadings 2 . mconcat . map (renderFunctionDoc Nothing) $
+       typeDocMethods td)
+  ]
+ where
+  ident = case mbmodname of
+    Just modname  -> mconcat [ "type-", modname, ".", typeDocName td ]
+    Nothing       -> mconcat [ "type-", typeDocName td ]
+
+-- Shift headings
+shiftHeadings :: Int -> B.Blocks -> B.Blocks
+shiftHeadings incr blks = flip walk blks $ \case
+  B.Header level attr inner -> B.Header (level + incr) attr inner
+  x -> x
+
+renderModuleDoc :: ModuleDoc -> B.Blocks
+renderModuleDoc moddoc =
+  let modname = moduleDocName moddoc
+  in mconcat
+  [ B.headerWith ("module-" <> modname, [], []) 1
+      (B.str $ "Module " <> modname)
+  , parseCommonMark (moduleDocDescription moddoc)
+  , if null (moduleDocFields moddoc)
+    then mempty
+    else
+      let ident = modname <> "-fields"
+      in B.headerWith (ident, [], []) 2 (B.str "Fields") <>
+         shiftHeadings 0 (mconcat (map (renderFieldDoc modname)
+                                   (moduleDocFields moddoc)))
+  , if null (moduleDocFunctions moddoc)
+    then mempty
+    else
+      let ident = modname <> "-functions"
+      in B.headerWith (ident, [], []) 2 (B.str "Functions") <>
+         (shiftHeadings 2 . mconcat . map (renderFunctionDoc $ Just modname) $
+          moduleDocFunctions moddoc)
+  , if null (moduleDocTypes moddoc)
+    then mempty
+    else
+      let ident = modname <> "-types"
+      in B.headerWith (ident, [], []) 2 (B.str "Types") <>
+         (shiftHeadings 2 . mconcat . map (renderTypeDoc $ Just modname) .
+          reverse $ moduleDocTypes moddoc)
+  ]
+
+parseCommonMark :: T.Text -> B.Blocks
+parseCommonMark txt =
+  let exts = extensionsFromList
+        [ Ext_wikilinks_title_after_pipe
+        , Ext_smart
+        ]
+      result = runPure $ do
+        Pandoc _ blks <- readCommonMark (def {readerExtensions = exts}) txt
+        return $ B.fromList blks
+  in either mempty id result
+
+appendInlines :: B.Blocks -> B.Inlines -> B.Blocks
+appendInlines blks inlns = case B.unMany blks of
+  front :|> (B.Para xs) -> B.Many front <> B.para (addTo xs)
+  front :|> (B.Plain xs) -> B.Many front <> B.plain (addTo xs)
+  _ -> blks <> B.para inlns
+ where addTo xs = B.fromList xs <> B.space <> inlns
+
+appendType :: B.Blocks -> TypeSpec -> B.Blocks
+appendType blks typespec =
+  appendInlines blks (B.str "(" <> typeToInlines typespec <> B.str ")")
+
+typeToInlines :: TypeSpec -> B.Inlines
+typeToInlines = \case
+  bt@BasicType{}   -> builtin $ tystr bt
+  NamedType "integer" -> builtin "integer"
+  NamedType name   -> B.linkWith ("", ["documented-type"], [])
+                        ("#" <> n2t name) mempty $ B.str (n2t name)
+  SeqType itemtype -> "{" <> typeToInlines itemtype <> ",...}"
+  SumType summands -> mconcat . intersperse (B.str "|") $ map typeToInlines summands
+  AnyType          -> "any"
+  x                -> tystr x
+ where
+  tystr = B.str . T.pack . typeSpecToString
+  n2t = UTF8.toText . fromName
+  builtin = B.spanWith ("", ["builtin-lua-type"], [])
+
+renderFunctionDoc :: Maybe T.Text -> FunctionDoc -> B.Blocks
+renderFunctionDoc mbmodule fndoc =
+  let name = case mbmodule of
+        Just _   ->  T.takeWhileEnd (/= '.') $ funDocName fndoc
+        Nothing  -> funDocName fndoc
+      ident = funDocName fndoc
+      level = 1
+      argsString = argslist (funDocParameters fndoc)
+      paramToDefItem p = ( B.code $ parameterName p
+                         , compactify
+                           [ appendType
+                               (parseCommonMark $ parameterDescription p)
+                               (parameterType p)
+                           ]
+                         )
+      paramlist = B.definitionList . map paramToDefItem $
+                  funDocParameters fndoc
+  in mconcat
+     [ B.headerWith (ident, [], []) level (B.str name)
+     , B.plain (B.code $ name <> " (" <> argsString <> ")")
+     , parseCommonMark (funDocDescription fndoc)
+     , if null (funDocParameters fndoc)
+       then mempty
+       else B.para "Parameters:" <> paramlist
+     , if funDocResults fndoc == ResultsDocList []
+       then mempty
+       else B.para "Returns:" <> renderResults (funDocResults fndoc)
+     , case funDocSince fndoc of
+         Nothing -> mempty
+         Just version ->
+           B.para $ B.emph $ "Since: " <> (B.str . T.pack $ showVersion version)
+     ]
+
+renderResults :: ResultsDoc -> B.Blocks
+renderResults (ResultsDocMult descr) = parseCommonMark descr
+renderResults (ResultsDocList rvd) = B.bulletList $ map renderResultVal rvd
+ where
+   renderResultVal (ResultValueDoc typespec descr) =
+     parseCommonMark descr `appendType` typespec
+
+argslist :: [ParameterDoc] -> T.Text
+argslist params =
+  -- Expect optional values to come after required values.
+  let (required, optional') = break parameterIsOptional params
+      reqs = map parameterName required
+      opts = map parameterName optional'
+  in if null opts
+     then T.intercalate ", " reqs
+     else T.intercalate ", " reqs <>
+          (if null required then "[" else "[, ") <>
+          T.intercalate "[, " opts <> T.replicate (length opts) "]"
+
+renderFieldDoc :: T.Text -> FieldDoc -> B.Blocks
+renderFieldDoc _modname fd =
+  B.headerWith (ident, [], []) 3 (B.str name) <>
+  appendType (parseCommonMark $ fieldDocDescription fd) (fieldDocType fd)
+ where
+  ident = fieldDocName fd
+  name = T.takeWhileEnd (/= '.') $ fieldDocName fd
diff --git a/pandoc-lua-engine/src/Text/Pandoc/Lua/Init.hs b/pandoc-lua-engine/src/Text/Pandoc/Lua/Init.hs
index 2756dc61b..546323761 100644
--- a/pandoc-lua-engine/src/Text/Pandoc/Lua/Init.hs
+++ b/pandoc-lua-engine/src/Text/Pandoc/Lua/Init.hs
@@ -3,7 +3,7 @@
 {-# LANGUAGE RankNTypes        #-}
 {- |
    Module      : Text.Pandoc.Lua.Init
-   Copyright   : © 2017-2024 Albert Krewinkel
+   Copyright   : © 2017-2026 Albert Krewinkel
    License     : GPL-2.0-or-later
    Maintainer  : Albert Krewinkel <[email protected]>
 
diff --git a/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/MediaBag.hs b/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/MediaBag.hs
index 412131560..7d0c76b80 100644
--- a/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/MediaBag.hs
+++ b/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/MediaBag.hs
@@ -104,8 +104,9 @@ insert = defun "insert"
           setMediaBag $ MB.insertMedia fp mmime contents mb
           return (Lua.NumResults 0))
   <#> stringParam "filepath" "filename and path relative to the output folder."
-  <#> opt (textParam "mimetype"
-           "the item's MIME type; omit if unknown or unavailable.")
+  <#> parameter (Lua.peekNilOr Lua.peekText) "string|nil" "mimetype"
+        "the item's MIME type; use `nil` if the MIME type is\
+        \ unknown or unavailable."
   <#> parameter Lua.peekLazyByteString "string" "contents"
         "the binary contents of the file."
   =#> []
diff --git a/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Path.hs b/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Path.hs
index efe00e03c..9334a2252 100644
--- a/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Path.hs
+++ b/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Path.hs
@@ -3,7 +3,7 @@
 {-# LANGUAGE TypeApplications    #-}
 {- |
    Module      : Text.Pandoc.Lua.Module.Path
-   Copyright   : © 2019-2024 Albert Krewinkel
+   Copyright   : © 2019-2026 Albert Krewinkel
    License     : GNU GPL, version 2 or above
 
    Maintainer  : Albert Krewinkel <[email protected]>
diff --git a/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Utils.hs b/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Utils.hs
index d4b7cea08..a5a6bde8b 100644
--- a/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Utils.hs
+++ b/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Utils.hs
@@ -4,7 +4,7 @@
 {-# LANGUAGE TypeApplications    #-}
 {- |
    Module      : Text.Pandoc.Lua.Module.Utils
-   Copyright   : Copyright © 2017-2026 Albert Krewinkel
+   Copyright   : © 2017-2026 Albert Krewinkel
    License     : GNU GPL, version 2 or above
 
    Maintainer  : Albert Krewinkel <[email protected]>
@@ -19,6 +19,7 @@ module Text.Pandoc.Lua.Module.Utils
 
 import Control.Applicative ((<|>))
 import Control.Monad ((<$!>))
+import Control.Monad.Except (MonadError (throwError))
 import Crypto.Hash (hashWith, SHA1(SHA1))
 import Data.Data (showConstr, toConstr)
 import Data.Default (def)
@@ -28,12 +29,17 @@ import HsLua as Lua
 import HsLua.Module.Version (peekVersionFuzzy, pushVersion)
 import Text.Pandoc.Citeproc (getReferences, processCitations)
 import Text.Pandoc.Definition
-import Text.Pandoc.Error (PandocError)
+import Text.Pandoc.Error (PandocError (PandocLuaError))
 import Text.Pandoc.Filter (applyJSONFilter)
+import Text.Pandoc.Format (FlavoredFormat (formatName), parseFlavoredFormat)
+import Text.Pandoc.Lua.Documentation (renderDocumentation)
 import Text.Pandoc.Lua.Filter (runFilterFile')
 import Text.Pandoc.Lua.Marshal.AST
+import Text.Pandoc.Lua.Marshal.Format (peekFlavoredFormat)
 import Text.Pandoc.Lua.Marshal.Reference
 import Text.Pandoc.Lua.PandocLua (PandocLua (unPandocLua))
+import Text.Pandoc.Options (WriterOptions (writerExtensions))
+import Text.Pandoc.Writers (Writer (..), getWriter)
 
 import qualified Data.Map as Map
 import qualified Data.Text as T
@@ -52,6 +58,7 @@ documentedModule = defmodule "pandoc.utils"
   `withFunctions`
     [ blocks_to_inlines `since` v[2,2,3]
     , citeproc          `since` v[2,19,1]
+    , documentation     `since` v[3,8,4]
     , equals            `since` v[2,5]
     , from_simple_table `since` v[2,11]
     , make_sections     `since` v[2,8]
@@ -67,8 +74,7 @@ documentedModule = defmodule "pandoc.utils"
 
     , defun "Version"
       ### liftPure (id @Version)
-      <#> parameter peekVersionFuzzy
-            "version string, list of integers, or integer"
+      <#> parameter peekVersionFuzzy "Version|string|{integer,...}|number"
             "v" "version description"
       =#> functionResult pushVersion "Version" "new Version object"
       #? "Creates a Version object."
@@ -125,6 +131,35 @@ citeproc = defun "citeproc"
       , "    end"
       ]
 
+documentation :: DocumentedFunction PandocError
+documentation = defun "documentation"
+  ### (\idx mformat -> do
+          docobj <- getdocumentation idx >>= \case
+            TypeNil -> fail "Undocumented object"
+            _ -> forcePeek $ peekDocumentationObject top
+          let blocks = renderDocumentation docobj
+          if maybe mempty formatName mformat == "blocks"
+            then pure . Left $ B.toList blocks
+            else unPandocLua $ do
+              flvrd <- maybe (parseFlavoredFormat "ansi") pure mformat
+              getWriter flvrd >>= \case
+                (TextWriter w, es) -> Right <$>
+                  w def{ writerExtensions = es } (B.doc blocks)
+                _ -> throwError $ PandocLuaError
+                  "ByteString writers are not supported here.")
+  <#> parameter pure "any" "object" "Retrieve documentation for this object"
+  <#> opt (parameter peekFlavoredFormat "string|table" "format"
+            "result format; defaults to `'ansi'`")
+  =#> functionResult (either pushBlocks pushText) "string|Blocks"
+        "rendered documentation"
+  #? "Return the documentation for a function or module defined by pandoc.\
+     \ Throws an error if there is no documentation for the given object.\n\
+     \\n\
+     \The result format can be any textual format accepted by `pandoc.write`,\
+     \ and the documentation will be returned in that format.\
+     \ Additionally, the special format `blocks` is accepted, in which case\
+     \ the documentation is returned as [[Blocks]]."
+
 equals :: LuaError e => DocumentedFunction e
 equals = defun "equals"
   ### equal
@@ -205,7 +240,7 @@ normalize_date :: DocumentedFunction e
 normalize_date = defun "normalize_date"
   ### liftPure Shared.normalizeDate
   <#> parameter peekText "string" "date" "the date string"
-  =#> functionResult (maybe pushnil pushText) "string or nil"
+  =#> functionResult (maybe pushnil pushText) "string|nil"
         "normalized date, or nil if normalization failed."
   #? T.unwords
   [ "Parse a date and convert (if possible) to \"YYYY-MM-DD\" format. We"
@@ -320,7 +355,8 @@ stringify = defun "stringify"
          , (fmap (const "") . peekAttr)
          , (fmap (const "") . peekListAttributes)
          ] idx)
-  <#> parameter pure "AST element" "element" "some pandoc AST element"
+  <#> parameter pure "Pandoc|Block|Inline|Caption|Cell|MetaValue"
+        "element" "some pandoc AST element"
   =#> functionResult pushText "string"
         "A plain string representation of the given element."
   #? T.unlines
diff --git a/tools/update-lua-module-docs.lua b/tools/update-lua-module-docs.lua
index 3f80ee28d..e74fb22aa 100644
--- a/tools/update-lua-module-docs.lua
+++ b/tools/update-lua-module-docs.lua
@@ -24,7 +24,13 @@ local registry = debug.getregistry()
 
 --- Retrieves the documentation object for the given value.
 local function documentation (value)
-  return registry['HsLua docs'][value]
+  local docobj = registry['HsLua docs'][value]
+  if type(docobj) == 'userdata' then
+    -- Get the table representation by calling the object
+    return docobj()
+  else
+    return docobj
+  end
 end
 
 --- Table containing all known modules
@@ -201,9 +207,8 @@ end
 -- @param modulename  name of the module that contains this function
 -- @return Documentation rendered as list of Blocks
 local function render_function (doc, level, modulename)
-  local name = doc.name
+  local name = doc.name:match('[^%.]*$')
   level = level or 1
-  local id = modulename and modulename .. '.' .. doc.name or ''
   local args = argslist(doc.parameters)
   local paramlist = DefinitionList(
     List(doc.parameters):map(
@@ -219,7 +224,7 @@ local function render_function (doc, level, modulename)
     )
   )
   return Blocks{
-    Header(level, name, {id}),
+    Header(level, name, {doc.name}),
     Plain{Code(string.format('%s (%s)', name, args))},
   } .. read_blocks(doc.description)
     .. List(#doc.parameters > 0 and {Para 'Parameters:'} or {})
@@ -236,8 +241,8 @@ end
 -- @param modulename  name of the module that contains this function
 -- @return {Block,...}
 local function render_field (field, level, modulename)
-  local id = modulename and modulename .. '.' .. field.name or ''
-  return Blocks{Header(level, field.name, {id})} ..
+  local name = field.name:match('[^.]*$')
+  return Blocks{Header(level, name, {field.name})} ..
     {Plain(read_inlines(field.description) .. type_to_inlines(field.type))}
 end
 
@@ -346,7 +351,7 @@ local function render_main_pandoc_module (doc)
   for _, field in ipairs(doc.fields) do
     if tostring(field.type) == 'string' then
       constants_section:extend(render_field(field, 2, "pandoc"))
-    elseif field.name:match '^[A-Z]' then
+    elseif field.name:match '^pandoc%.[A-Z]' then
       -- Ignore (these are the `Block` and `Inline` tables)
     else
       fields:insert(field)
@@ -360,7 +365,7 @@ local function render_main_pandoc_module (doc)
     else
       functions:insert(fn)
     end
-    if fn.name == 'SimpleTable' then
+    if fn.name == 'pandoc.SimpleTable' then
       stop_rendering = true
     end
   end
@@ -392,10 +397,10 @@ local function process_document (input, blocks, start)
   if mstart and mstop and module_name then
     print('Generating docs for module ' .. module_name)
     blocks:insert(rawmd(input:sub(start, mstop)))
-    local object = modules[module_name] or modules[module_name:gsub('^pandoc%.', '')]
+    local object = require(module_name)
     local docblocks = (object == pandoc)
       and render_main_pandoc_module(documentation(object))
-      or render_module(documentation(object))
+      or pandoc.utils.documentation(object, 'blocks')
     blocks:extend(docblocks)
     return process_document(input, blocks, input:find(autogen_end, mstop) or -1)
   else
@@ -411,12 +416,15 @@ function Reader (inputs)
   local blocks = process_document(tostring(inputs), Blocks{}, 1)
   blocks = blocks:walk {
     Link = function (link)
-      if link.classes == pandoc.List{'wikilink'} then
+      if link.classes == pandoc.List{'documented-type'} or
+         link.classes == pandoc.List{'wikilink'} then
         link.classes = {}
-        if known_types[link.target] then
-          link.target = '#' .. known_types[link.target]
+        local ident = link.target:gsub('^#', '')
+        if known_types[ident] then
+          link.target = '#' .. known_types[ident]
         else
-          warn('Unknown type: ' .. link.target)
+          link.target = '#' .. ident
+          warn('Unknown type: ' .. ident)
         end
         return link
       end
@@ -432,16 +440,3 @@ function Reader (inputs)
   }
   return Pandoc(blocks)
 end
-
--- For usage as a standalone script.
--- E.g.
---
---     pandoc lua module-docs.lua
---
--- Generate Markdown docs for the given module and writes them to stdout.
-if arg and arg[1] then
-  local module_name = arg[1]
-  local object = modules[module_name]
-  local blocks = render_module(documentation(object))
-  print(write(Pandoc(blocks), 'markdown'))
-end