View source for ConTeXt and Lua programming/ConTeXt Development/LMTX

Since April 2019, there is a new implementation of ConTeXt, named '''ConTeXt LMTX'''. It is tuned for [[LuaMetaTeX]], the lean and mean successor of the [[ConTeXt and Lua programming/ConTeXt Development/LuaTeX|LuaTeX]] engine.

From Hans’ introductory article in TUGBoat:
: More than decade after introducing the ConTeXt version for LuaTeX, flagged [[ConTeXt_and_Lua_programming/ConTeXt_Development/Mark IV|Mark IV]] (the version known as [[ConTeXt_and_Lua_programming/ConTeXt_Development/Mark II|Mark II]] ran under more traditional TeX engines), it is time for something new. As MkVI, MkIX and MkXI are already taken for special variants of MkIV files a new acronym was coined: LMTX. Such a sequence of letters must sound somewhat fancy but it actually has a meaning, or better: it has several. One is that it stands for LuaMetaTeX, an indication of an engine to be used. But one can also think of the components that make up ConTeXt code: Lua, MetaPost, TeX, and XML. But once it is clear to a user what (s)he is dealing with, it can also indicate a “Lean and Mean TeX eXperience”.

== The LuaMetaTeX engine ==

The big difference between LMTX and all previous versions of ConTeXt is that LMTX uses a compilation and scripting engine that is specifically developed with ConTeXt in mind: LuaMetaTeX (the executable is named `luametatex`). This new engine builds heavily on the LuaTeX engine, but it has been optimised heavily for ConTeXt use:

* There are no external dependencies except for thee core `libc` and `libm` runtimes.
* There is no PDF backend code, all PDF generation is handled by ConTeXt’s Lua code.
* There is no `fontloader` lua interface library, (OpenType) font loading is handled by ConTeXt’s Lua code.
* There are no `img` and `pdf` (poppler-based) Lua interface libraries (the latter is replaced by the leaner dedicated library `epdf`).
* Various extensions have been made to other Lua interface libraries.

When it comes to typesetting, `luametatex` is (at least for now) 100% compatible with LuaTeX > 1.0.

== The LMTX distribution ==

Some extra scripting extensions in the engine have made it much easier to produce a standalone distribution of ConTeXt that is not only compact, but also capable of partial updates. See [[Input_and_compilation/Installation|Installation]] for the new installation and update process.

Of course the new distribution defaults to running LMTX. But it can still process input using LuaTeX ([[ConTeXt_and_Lua_programming/ConTeXt_Development/Mark IV]]) as well. You can do this by running

<pre>
  context --luatex
</pre>
This works because the distribution contains all of the [[ConTeXt_and_Lua_programming/ConTeXt_Development/Mark IV]] source code as well as a `luatex` binary.

The new installation no longer contains the [[ConTeXt_and_Lua_programming/ConTeXt_Development/Mark II]] source code or binaries, and is therefore unable to run it. 

== How to check for newer versions? ==

You might check for newer versions with the following command (in ''Unix''):

<pre>
 curl -I http://www.pragma-ade.nl/context/latest/cont-tmf.zip 2>&1 | grep Last-Modified
</pre>

Your installed version is displayed with the following commands:

<pre>
 context --version && luametatex --version
</pre>

== LMTX doesn’t update? ==

The install script (`install.bat` or `install.sh`) doesn’t update itself. 

This is the reason why a new version may have been released, but your installed LMTX might not update.

If the install script has been changed, you need to replace it manually with the newest version before updating your LMTX installation.

= Further reading =
* Hans' introductory [https://tug.org/TUGboat/tb40-1/tb124hagen-lmtx.pdf article] in TUGBoat 40:1.
* The official page '''[http://www.pragma-ade.nl/install.htm Installing CONTEXT LMTX ]''' is hosted by Pragma-Ade, which also provides
** a 2 pages '''[http://lmtx.pragma-ade.nl/install-lmtx/installation.pdf installation guide]''',
** a 1 page [http://distribution.contextgarden.net/current/context/experimental/doc/context/documents/general/leaflets/leaflet-context.pdf leaflet for ConTeXt LMTX]
** a 1 page [http://distribution.contextgarden.net/current/context/experimental/doc/context/documents/general/leaflets/leaflet-luametatex.pdf leaflet for LuaMetaTeX].

[[Category:Development]]
[[Category:Installation]]
[[Category:Programming and Databases]]