LuaTeX Lua API

Type definitions for the Lua API of LuaTeX and related projects.

LuaTeX has a very large Lua API. This project tries to make this API accessible in the text editor of your choice. This is made possible by the lua-language-server - a server that implements the Language Server Protocol (LSP) for the Lua language. Features such as code completion, syntax highlighting and marking of warnings and errors, should therefore not only be possible in Visual Studio Code, but in a large number of editors that support the LSP.

Subprojects

Distribution ...

via CTAN

The type definitions are published on CTAN as a single file to avoid cluttering the CTAN directory with many individual Lua files. Since this one file is just under 1.5 MB in size, a configuration must be made so that the language server can load the file. The following configuration example sets the preload file size to a maximum of 5000 kB.

{
    "Lua.workspace.preloadFileSize": 5000,
}

There are several ways to include type definitions in a project. The easiest way is to copy the file into the project folder. Or you can use the configuration Lua.workspace.library:

{
    "Lua.workspace.library": ["/path/to/luatex-type-definitions.lua"]
}

via Visual Studio Code Extension

Visual Studio Code LuaTeX Extension ← library

via LuaCATS git respositories

LuaCATS is a Github organisation and stands for “Lua Comment And Type System”. This organization provides a place for community projects to live. These projects are addons for popular libraries/frameworks. The repositories in this organization are used by LLS-Addons, a repository that is used by the addon manager of the VS Code extension for the Lua Language Server.

All related LuaCATS repositories

This repositories in LuaCATS are related to this project:

Upstream LuaCATS repositories

The following repositories are upstream projects. This means: The type definitions are developed in a LuaCATS repository and pulled in by this project.

Downstream LuaCATS repositories

The following repositories are downstream projects. This means: The type definitions are developed in this project. They are then pushed into a LuaCATS repository.

LuaCATS: tex-lualatex ← library/lualatex
LuaCATS: tex-luatex ← library/luatex
LuaCATS: tex-lualibs ← library/lualibs
LuaCATS: tex-luametatex ← library/luametatex

Directory structure of the repository

In the subfolder library are files named after the global libraries they document. For example, the library/tex.lua file contains the documentation for the tex library. These Lua files don’t contain real Lua code. They consist only of function bodies and empty tables. The main focus is in the docstrings.

The API documentation is written in a well documented annotation format. This format is based on the EmmyLua format. Unfortunately, the Lua community has not yet been able to agree on a standarized annotation format. Many Lua project are documented in the LDoc format. However, the differences between these formats are marginal.

Directory `library`

The actual definitions are located in the directory library. This directory is divided into further subdirectories. In the folder luatex you will find the definitions that the engine LuaTeX provides. The folder lualibs documents the extension library of the same name. If you use lualatex, you may be interested in the folder of the same name.

Directory `resources`

The folder resources contains TeX manuals and HTML online documentation converted into Lua docstrings.

Directory `examples`

The example folder contains TeX and Lua files for demonstrating and testing the documented Lua API.

Current version

2025/07/24 v0.2.0

License

Copyright (C) 2022-2025 by Josef Friedrich josef@friedrich.rocks

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see https://www.gnu.org/licenses/.

Installation / Setup for Visual Studio Code

Install Visual Studio Code and the lua-language-server.

git clone https://github.com/Josef-Friedrich/LuaTeX_Lua-API.git

.vscode/settings.json:

{
"Lua.workspace.library": [
    "<repo>/library"
  ]
}

How to contribute

The preferred method of contributing to the project is via Github pull requests. You can also email patches to josef@friedrich.rocks. It is ok if you only document the data types of the input parameters.

Use imperative mood for the first line: https://peps.python.org/pep-0257/

Please contribute! messages

Default message:

---😱 [Types](https://github.com/Josef-Friedrich/LuaTeX_Lua-API/blob/main/library/luatex/pdf.lua) incomplete or incorrect? 🙏 [Please contribute!](https://github.com/Josef-Friedrich/LuaTeX_Lua-API/pulls)

No documentation at all:

---
---Warning! Undocumented code!<p>
---TODO: Please contribute
---https://github.com/Josef-Friedrich/LuaTeX_Lua-API#how-to-contribute

Minimal example of `tex.sp()`

---
---@param s string
function tex.sp(s) end

Less minimal example of `tex.sp()`

---
---@param s string
---
---@return integer
function tex.sp(s) end

Or if you have more time you can also expand the documentation to this level:

Prime example of `tex.sp()`

---@meta

tex = {}

---
---Convert a string `s` that represents an explicit
---dimension into an integer number of scaled points.
---
---For parsing the string, the same scanning and conversion rules are used that
---*LuaTeX* would use if it was scanning a dimension specifier in its *TeX*-like
---input language (this includes generating errors for bad values), expect for the
---following:
---
---* only explicit values are allowed, control sequences are not handled
---* infinite dimension units (`fil...`) are forbidden
---* `mu` units do not generate an error (but may not be useful either)
---
---__Example:__
---
---```lua
---local scaled_points = tex.sp('1cm')
---print(scaled_points) -- 1864679
---```
---
---__Reference:__
---
---* `LuaTeX` manual: 10.3.15.5 `sp` page 204
---* Source file of the `LuaTeX` manual: [luatex-tex.tex#L1386-L1413](https://gitlab.lisn.upsaclay.fr/texlive/luatex/-/blob/f52b099f3e01d53dc03b315e1909245c3d5418d3/manual/luatex-tex.tex#L1386-L1413)
---
---@param s string # A string to convert into scaled points.
---
---@return integer # The dimension in the scaled points format.
function tex.sp(s) end

The docstring above is rendered as follows in Visual Studio Code:

The description text can be or was taken from the official LuaTeX reference manual. In the project folder resources/manuals/luatex you will find slightly edited Lua versions of the LuaTeX manual sources.

This quick hacked and very ugly Python script resources/manuals/convert-tex-to-lua-docstrings.py was used to convert the source files.

Navigation table `_N`

Some Lua files contain a table named _N. _N stands for navigation. With the help of this table and the outline view of the editor, it is easier to navigate through the documentation. The name is inspired by the global Lua table _G. Many parts of the documentation, such as the definition of the various Node classes, are not shown in the outline. In the released version, this navigation table is removed using the manage.py management script.

---A helper table to better navigate through the documentation using the
---outline: https://github.com/Josef-Friedrich/LuaTeX_Lua-API#navigation-table-_n
_N = {}

The different node types are defined as classes. Since this class definition takes place entirely in the comments, it is not displayed in the outline.

_N.hlist = 0

---@class HlistNode: ListNode

_N.vlist = 1

---@class VlistNode: ListNode

The following example refers to section “8.7.2 is_node” on page 149 in the LuaTeX documentation.

_N._8_7_2_is_node = "page 149"

Documentation of function overloading

LuaTeX makes extensive use of function overloading. The following example is taken from the LuaTeX manual:

<number> w, <number> h, <number> d =
  node.dimensions(<node> n)
<number> w, <number> h, <number> d =
  node.dimensions(<node> n, <string> dir)
<number> w, <number> h, <number> d =
  node.dimensions(<node> n, <node> t)
<number> w, <number> h, <number> d =
  node.dimensions(<node> n, <node> t, <string> dir)
<number> w, <number> h, <number> d =
  node.dimensions(<number> glue_set, <number> glue_sign, <number> glue_order, <node> n)
<number> w, <number> h, <number> d =
  node.dimensions(<number> glue_set, <number> glue_sign, <number> glue_order, <node> n, <string> dir)
<number> w, <number> h, <number> d =
  node.dimensions(<number> glue_set, <number> glue_sign, <number> glue_order, <node> n, <node> t)
<number> w, <number> h, <number> d =
  node.dimensions(<number> glue_set, <number> glue_sign, <number> glue_order, <node> n, <node> t, <string> dir)

This can easily be done by documenting the function with the same name but different signatures multiple times.

Issue for further improvement of the function loading

Function overloading in tex.sp()

Documentation of nodes

A node (object) can be described by the @class annotation and provided with some documentation about its attributes using @field. There is a base class Node for all node type classes.

---
---A node that comprise actual typesetting commands. A few fields are
---present in all nodes regardless of their type, these are:
---
---@class Node
---@field next Node|nil # the next node in a list, or nil
---@field prev Node|nil # That prev field is always present, but only initialized on explicit request ...

The KernNode class for example inherits from Node and represents a kern node.

---
---The `kern` command creates such nodes but for instance the font and math
---machinery can also add them.
---
---@class KernNode: Node
---@field subtype KernNodeSubtype
---@field kern integer # Fixed horizontal or vertical advance (in scaled points)

---@alias KernNodeSubtype
---|0 # fontkern
---|1 # userkern
---|2 # accentkern
---|3 # italiccorrection

The @cast annotation forces a unspecific node to a distinct node type.

while n do
  if n.id == node.id('kern') then
    ---@cast n KernNode
    print(n.kern)
  end
  n = n.next
end

Use --[[@as <node type>]] to force a node type onto an expression.

local kern = node.new('kern') --[[@as KernNode]]

Documentation of callback functions

How a callback function is documented is shown using the pre_linebreak_filter as an example.

@alias `PreLinebreakFilterGroupCode`

---
---The string called `groupcode` identifies the nodelist's context within
---*TeX*'s processing. The range of possibilities is given in the table below, but
---not all of those can actually appear in `pre_linebreak_filter`, some are
---for the `hpack_filter` and `vpack_filter` callbacks that will be
---explained in the next two paragraphs.
---@alias PreLinebreakFilterGroupCode
---|'' # main vertical list
---|'hbox' # hbox` in horizontal mode
---|'adjusted_hbox' #hbox` in vertical mode
---|'vbox' # vbox`
---|'vtop' # vtop' #
---|'align' # halign` or `valign`
---|'disc' # discretionaries
---|'insert' # packaging an insert
---|'vcenter' # vcenter`
---|'local_box' # localleftbox` or `localrightbox`
---|'split_off' # top of a `vsplit`
---|'split_keep' # remainder of a `vsplit`
---|'align_set' # alignment cell
---|'fin_row' # alignment row

@alias `NodeCallbackReturn`

---
---As for all the callbacks that deal with nodes, the return value can be one of
---three things:
---
---* boolean `true` signals successful processing
---* `<node>` signals that the “head” node should be replaced by the
---  returned node
---* boolean `false` signals that the “head” node list should be
---  ignored and flushed from memory
---@alias NodeCallbackReturn true|false|Node

@alias `PreLinebreakFilter`

---
---# `pre_linebreak_filter` callback
---
---This callback is called just before *LuaTeX* starts converting a list of nodes
---into a stack of `hbox`es, after the addition of `parfillskip`.
---
---```lua
------@type PreLinebreakFilter
---function(head, groupcode)
---  --- true|false|node
---  return true
---end
---```
---
---This callback does not replace any internal code.
---@alias PreLinebreakFilter fun(head: Node, groupcode: PreLinebreakFilterGroupCode): NodeCallbackReturn

Annotation your custom callback function with @type.

---@type PreLinebreakFilter
local function visit_nodes(head, group)
  return true
end

luatexbase.add_to_callback('pre_linebreak_filter', visit_nodes, 'visit nodes')

Quick info node.id(type)

Type error in node.id(type)

node.id(type) type definition

Quick info node.write(n)

Documentation for the field data of the pdf_colorstack node:

Documentation

Howtos

Other type definition / stub repos:

References

---
---__Reference:__
---
---* Corresponding C source code: [ltexlib.c#L1430-L1436](https://gitlab.lisn.upsaclay.fr/texlive/luatex/-/blob/f52b099f3e01d53dc03b315e1909245c3d5418d3/source/texk/web2c/luatexdir/lua/ltexlib.c#L1430-L1436)
---* Source file of the `LuaTeX` manual: [luatex-nodes.tex#L1199-L1211](https://gitlab.lisn.upsaclay.fr/texlive/luatex/-/blob/f52b099f3e01d53dc03b315e1909245c3d5418d3/manual/luatex-nodes.tex#L1199-L1211)
---* Corresponding plain TeX control sequence: [\sfcode](https://www.tug.org/utilities/plain/cseq.html#sfcode-rp)
---* Victor Eijkhout. “TeX by Topic” (1991, 2007) [page 185](http://mirrors.ctan.org/info/texbytopic/TeXbyTopic.pdf)
---* Donald Ervin Knuth. “The TexBook” (1984): page 76. Also: 76, 271, 285, 363, 433. [TeX-Source](https://ctan.org/tex-archive/systems/knuth/dist/tex/texbook.tex) [PDF](https://visualmatheditor.equatheque.net/doc/texbook.pdf)
---David Bausum. “TeX Reference Manual” (2002) [](https://www.tug.org/utilities/plain/cseq.html)

---
---__Reference:__
---
---* Source file of the `LuaTeX` manual: []()
---

lualibs

/usr/local/texlive/texmf-dist/tex/luatex/lualibs/lualibs-basic-merged.lua /usr/local/texlive/texmf-dist/tex/luatex/lualibs/lualibs-extended-merged.lua

dir.lua

Filename	ConTeXt	LaTeX
dir.lua	context/base/mkiv/l-dir.lua	lualibs-dir.lua

file.lua

Filename	ConTeXt	LaTeX
file.lua	context/base/mkiv/l-file.lua	lualibs-file.lua

gzip.lua

Filename	ConTeXt	LaTeX
gzip.lua		lualibs-util-zip.lua

io.lua

Filename	ConTeXt	LaTeX
	context/base/mkiv/l-io.lua	lualibs-io.lua

lfs.lua

Filename	ConTeXt	LaTeX
lfs.lua

lpeg.lua

Filename	ConTeXt	LaTeX
lpeg.lua	context/base/mkiv/l-lpeg.lua	lualibs-lpeg.lua

lualibs.lua

Filename	ConTeXt	LaTeX
lualibs.lua

lua.lua

Filename	ConTeXt	LaTeX
lua.lua

math.lua

Filename	ConTeXt	LaTeX
math.lua

modules.lua

Filename	ConTeXt	LaTeX
modules.lua

number.lua

Filename	ConTeXt	LaTeX
number.lua	context/base/mkiv/l-number.lua	lualibs-number.lua

os.lua

Filename	ConTeXt	LaTeX
os.lua	context/base/mkiv/l-os.lua	lualibs-os.lua

package.lua

Filename	ConTeXt	LaTeX
package.lua	context/base/mkiv/l-package.lua	lualibs-package.lua

set.lua

Filename	ConTeXt	LaTeX
set.lua	context/base/mkiv/l-set.lua	lualibs-set.lua

statistics.lua

Filename	ConTeXt	LaTeX
statistics.lua

string.lua

Filename	ConTeXt	LaTeX
string.lua	context/base/mkiv/l-string.lua	lualibs-string.lua
boolean.lua	context/base/mkiv/l-boolean.lua	lualibs-boolean.lua
lpeg.lua	context/base/mkiv/l-lpeg.lua	lualibs-lpeg.lua
unicode.lua	context/base/mkiv/l-unicode.lua	lualibs-unicode.lua
util-dim.lua (`dimensions`)	context/base/mkiv/util-dim.lua	lualibs-util-dim.lua
util-str.lua (`strings`)	context/base/mkiv/util-str.lua	lualibs-util-str.lua

table.lua

Filename	ConTeXt	LaTeX
table.lua	context/base/mkiv/l-table.lua	lualibs-table.lua

trackers.lua

Filename	ConTeXt	LaTeX
trackers.lua

url.lua

Filename	ConTeXt	LaTeX
url.lua	context/base/mkiv/l-url.lua	lualibs-url.lua

utf.lua

Filename	ConTeXt	LaTeX
utf.lua

utilities.lua |

Filename	ConTeXt	LaTeX
util-deb.lua (`debugger`)	context/base/mkiv/util-deb.lua	lualibs-util-deb.lua
util-fil.lua (`files`)	context/base/mkiv/util-fil.lua	lualibs-util-fil.lua
util-jsn.lua (`json`)	context/base/mkiv/util-jsn.lua	lualibs-util-jsn.lua
util-lua.lua (`lua`)	context/base/mkiv/util-lua.lua	lualibs-util-lua.lua
util-prs.lua (`parsers`)	context/base/mkiv/util-prs.lua	lualibs-util-prs.lua
util-sac.lua (`streams` (string access))	context/base/mkiv/util-sac.lua	lualibs-util-sac.lua
util-sta.lua (`stacker`)	context/base/mkiv/util-sta.lua	lualibs-util-sta.lua
util-sto.lua (`storage`)	context/base/mkiv/util-sto.lua	lualibs-util-sto.lua
util-str.lua (`strings`)	context/base/mkiv/util-str.lua	lualibs-util-str.lua
util-tpl.lua (`templates`)	context/base/mkiv/util-tpl.lua	lualibs-util-tpl.lua

xzip.lua

Global namespaces

The Makefile provides targets for printing the global namespace available on the specific engines. The Makefile uses some Lua functions to output all functions and tables of the global namespace that can be found in utils.lua.

To print the LuaTeX global namespace:

make namespace_luatex

To print the LuaMetaTeX global namespace:

make namespace_luametatex

Name		Name	Last commit message	Last commit date
Latest commit History 631 Commits
.vscode		.vscode
examples		examples
library		library
resources		resources
.gitignore		.gitignore
.gitmodules		.gitmodules
CHANGELOG.md		CHANGELOG.md
LICENSE		LICENSE
Makefile		Makefile
README.md		README.md
luatex-type-definitions-doc.tex		luatex-type-definitions-doc.tex
manage.py		manage.py
search.sh		search.sh

License

Josef-Friedrich/LuaTeX_Lua-API

Folders and files

Latest commit

History

Repository files navigation

LuaTeX Lua API

Subprojects

Distribution ...

via CTAN

via Visual Studio Code Extension

via LuaCATS git respositories

All related LuaCATS repositories

Upstream LuaCATS repositories

Downstream LuaCATS repositories

Directory structure of the repository

Directory library

Directory resources

Directory examples

Current version

License

Copyright (C) 2022-2025 by Josef Friedrich josef@friedrich.rocks

Installation / Setup for Visual Studio Code

How to contribute

Minimal example of tex.sp()

Less minimal example of tex.sp()

Prime example of tex.sp()

Navigation table _N

Documentation of function overloading

Documentation of nodes

Documentation of callback functions

@alias PreLinebreakFilterGroupCode

@alias NodeCallbackReturn

@alias PreLinebreakFilter

Documentation

Howtos

Other type definition / stub repos:

References

lualibs

dir.lua

file.lua

gzip.lua

io.lua

lfs.lua

lpeg.lua

lualibs.lua

lua.lua

math.lua

modules.lua

number.lua

os.lua

package.lua

set.lua

statistics.lua

string.lua

table.lua

trackers.lua

url.lua

utf.lua

utilities.lua |

xzip.lua

Global namespaces

About

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Languages

Directory `library`

Directory `resources`

Directory `examples`

Minimal example of `tex.sp()`

Less minimal example of `tex.sp()`

Prime example of `tex.sp()`

Navigation table `_N`

@alias `PreLinebreakFilterGroupCode`

@alias `NodeCallbackReturn`

@alias `PreLinebreakFilter`