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diff --git a/doc/context/presentations/context/2020/context-2020-luametatex.tex b/doc/context/presentations/context/2020/context-2020-luametatex.tex new file mode 100644 index 000000000..10b57660e --- /dev/null +++ b/doc/context/presentations/context/2020/context-2020-luametatex.tex @@ -0,0 +1,529 @@ +% language=us + +\usemodule[present-boring,abbreviations-logos] + +\startdocument + [title={LUAMETATEX}, + banner={where do we stand}, + location={context\enspace {\bf 2020}\enspace meeting}] + +\starttitle[title=When it started] + +\startitemize + +\startitem + About three years ago the idea came up to go this route. +\stopitem +\startitem + At the 2018 meeting it was first mentioned and those present were okay with + it. +\stopitem +\startitem + Early 2019 the first beta release took place. +\stopitem +\startitem + At the 2019 meeting the first more official version was presented. +\stopitem +\startitem + Around the 2020 meeting we have more or less arrived at what I had in mind. +\stopitem +\startitem + At the 2021 meeting I expect the code to be stable and repositories to be set + up. +\stopitem +\startitem + At the 2022 meeting we can make the official transition from \MKIV\ to \LMTX. +\stopitem +\startitem + Some new options are only enabled in my local \type {cont-exp.tex} file. +\stopitem +\startitem + Knowing that Wolfgang keeps an eye on all those changes makes me more daring. +\stopitem +\startitem + We aim to get less (but more efficient) macro code that on the average looks + better. +\stopitem + +\stopitemize + +\stoptitle + +\starttitle[title=Why it started] + +\startitemize + +\startitem + There was an increasing pressure for a stable \LUATEX. +\stopitem +\startitem + There should be no more changes to the interfaces, no more extensions. +\stopitem +\startitem + One can run into interesting comments on the web (as usual), like + \startitemize[packed] + \startitem The \LUATEX\ program has \quote {many bugs}. \stopitem + \startitem The \LUATEX\ manual is bad. \stopitem + \startitem The \LUATEX\ program is too slow to be useful. \stopitem + \startitem The \LUATEX\ program will never end up in distributions. \stopitem + \startitem The \LUATEX\ project is funded and developed in a commercial setting. \stopitem + \stopitemize +\stopitem +\startitem + I won't comment on how I read these (demotivating) comments because \unknown +\stopitem +\startitem + \unknown\ it anyway often says more about the writer (attitudes) than about + \LUATEX. +\stopitem +\startitem + I also looks like (non \CONTEXT) users are charmed by \LUATEX, and the more + they code, the more we need to freeze. +\stopitem +\startitem + So, hopefully, the \LUAMETATEX\ development does not interfere badly with + developments outside the \CONTEXT\ community. +\stopitem + +\stopitemize + +\stoptitle + +\starttitle[title=The development] + +The summary on the next pages is partial. More can be found in articles and +documents that come with the distribution. + +\startitemize + +\startitem + \LUATEX\ started out as \CWEB\ code \unknown\ that eventually became just + \CCODE\ \unknown\ which in \LUAMETATEX\ has been detached from the (complex) + infrastructure. +\stopitem +\startitem + The basic idea is to only keep the core of \TEX, but for instance font + loading, file handling and the backend are gone. +\stopitem +\startitem + As a consequence the code has been reorganized (shuffled around). +\stopitem +\startitem + I experimented a lot without bothering about usage elsewhere and I like the + result so far. +\stopitem +\startitem + The \CONTEXT\ distribution will at some point ship with the source. +\stopitem + +\stopitemize + +\starttitle[title=File handling] + +\startitemize + +\startitem + All file handling goes via \LUA, also read and write related primitives. +\stopitem +\startitem + The same is true for terminal (console) handling. +\stopitem +\startitem + Part of that (the writing) was actually kind of extension code in \TEX\ and + partly a system dependency. +\stopitem +\startitem + The \ETEX\ pseudo file \type {\scantokens} primitive uses the same mechanism + as \LUA\ does. +\stopitem + +\stopitemize + +\stoptitle + +\starttitle[title=The macro machinery] + +\startitemize + +\startitem + There are extensions to the way macro arguments are handled (less clumsy + macros). +\stopitem +\startitem + There are extra if tests (makes for nicer macros). +\stopitem +\startitem + Else branches in conditions can be collapsed using \type {\orelse} and \type + {\orunless} which gives cleaner low level code. +\stopitem +\startitem + Tracing gives more detail about node properties and also shows attributes. +\stopitem +\startitem + Some new data carriers have been added that can be played with from \LUA . +\stopitem +\startitem + Macros can efficiently be frozen (new) and protected (redone) and the + concepts \quote {long} and \type {outer} are gone. \footnote {In \CONTEXT\ + macros were always \type {\long} and never \type {\outer}. Most commands were + unexpandable (also in \MKII, pre \ETEX). So, users won't notice this.} +\stopitem +\startitem + Saving and restoring is somewhat more efficient (partly a side effect of + wider memory). +\stopitem + +\stopitemize + +\stoptitle + +\starttitle[title=Language] + +\startitemize + +\startitem + Language control settings now use less parameters but bit sets instead. +\stopitem +\startitem + Only basic parameters are stored in the format file now. +\stopitem +\startitem + There are all kind of small improvements. +\stopitem + +\stopitemize + +\stoptitle + +\starttitle[title=Typesetting] + +\startitemize + +\startitem + Attributes (the lists and states) are implemented more efficiently. +\stopitem +\startitem + The paragraph state is stored with the paragraph. +\stopitem +\startitem + Paragraphs can be normalized and options are now set with bit sets. +\stopitem +\startitem + Boxes carry orientation related information (offsets, rotation, etc). +\stopitem +\startitem + Some nodes carry more information. +\stopitem +\startitem + Directions are mostly gone (it's up to the backend). +\stopitem +\startitem + Migrated content is optionally kept with boxes. +\stopitem + +\stopitemize + +\stoptitle + +\starttitle[title=Math] + +\startitemize + +\startitem + Some math concepts have been extended (like prescripts and some more + control over styles). +\stopitem +\startitem + There are plenty of new control details. +\stopitem +\startitem + The math parameter settings obey grouping in a math list. +\stopitem +\startitem + We can have math in discretionaries in text and more advanced discretionaries + in math as well. +\stopitem + +\stopitemize + +\stoptitle + +\starttitle[title=Fonts] + +\startitemize + +\startitem + Font specification information no longer uses the string pool (which saves a + lot). +\stopitem +\startitem + Of course we still have the basic font handler. +\stopitem +\startitem + We only store what is needed for traditional \TEX\ font handling. +\stopitem +\startitem + Virtual fonts are even more virtual (also a backend thing) so we can have + more features. +\stopitem + +\stopitemize + +\stoptitle + +\starttitle[title=The code] + +\startitemize + +\startitem + Artifacts from \PASCAL\ and \CWEB\ have been removed. +\stopitem +\startitem + Languages, fonts, marks etc are no longer \quote {register} based. +\stopitem +\startitem + The token interface is more abstract and no longer presents strange numbers. +\stopitem +\startitem + Some internals have been reconstructed because of cleaner \LUA\ interfacing. +\stopitem +\startitem + A side effect of this is better abstraction of the equivalent ranges. +\stopitem +\startitem + The code has been made more abstract (and looks easier in e.g. Visual Studio). +\stopitem +\startitem + The compile farm is used to check if compilation works out of the box. +\stopitem +\startitem + Compilation is fast and easy, otherwise this project was not possible. +\stopitem +\startitem + Readability of the code is constantly improved (the usual: has to look okay + in my editor). +\stopitem +\startitem + The code has been made mostly independent of specific operating system needs. +\stopitem +\startitem + Wide characters are dealt with in Windows interfaces. +\stopitem + +\stopitemize + +\stoptitle + +\starttitle[title=Libraries] + +\startitemize + +\startitem + We really want to stay lean and mean: the engine is also a \LUA\ engine. +\stopitem +\startitem + All code is included, a few libraries are used, but these are small, old and + stable. +\stopitem +\startitem + In addition some helper libraries are made (including pplib by Pawel). +\stopitem +\startitem + What we ship is what you get: \CONTEXT\ will not depend on more than that. +\stopitem +\startitem + If something is updated (at all) the differences are checked first. +\stopitem + +\stopitemize + +\stoptitle + +\starttitle[title=The \LUA\ engine] + +\startitemize + +\startitem + We use the latest (even alpha) \LUA\ (5.4) because \LUAMETATEX\ is a good + test. +\stopitem +\startitem + There is no support for \LUAJIT\ and the \FFI\ interface is gone. +\stopitem +\startitem + There is a limited set of libraries that we support but no code is (and will + be) included. +\stopitem +\startitem + There are less callbacks (because we only have a frontend). +\stopitem +\startitem + There are more token scanners and some options have been added. +\stopitem + +\stopitemize + +\stoptitle + +\starttitle[title=Efficiency] + +\startitemize + +\startitem + We benefit some more from the wider memory words (some constructs could go). +\stopitem +\startitem + The format file is smaller and not longer compressed. +\stopitem +\startitem + Memory management is now mostly dynamic and usage is much lower. +\stopitem +\startitem + There are more statistics (also as side effect of memory management). +\stopitem +\startitem + Dumping the format has been made a bit more robust and is faster. +\stopitem +\startitem + The core engine performs a bit better (machines don't get that much faster). +\stopitem +\startitem + We want to be prepared for future architectures. +\stopitem +\startitem + We manage to keep the binary way below 3 MB. +\stopitem +\startitem + The lot runs quite well on e.g.\ a Raspberry Pi 4. +\stopitem + +\stopitemize + +\starttitle[title=Upgraded \METAPOST] + +\startitemize + +\startitem + All (eight bit) font stuff has been stripped from the \METAPOST\ library. +\stopitem +\startitem + The library no longer has a \POSTSCRIPT\ backend. +\stopitem +\startitem + The library provides scanners that make extensions possible. +\stopitem +\startitem + All file \IO\ goes via \LUA. +\stopitem +\startitem + There are a few additions like pre|/|postscripts for clip and bounding boxes. +\stopitem +\stopitemize + +\stoptitle + +\starttitle[title=Praise for the users] + +\startitemize + +\startitem + Much has been done and I probably forget to mention a lot. +\stopitem +\startitem + The number of bugs is relative small compared to what gets changed and added. +\stopitem +\startitem + The test suite gets ran very often, also to check if performance is okay. +\stopitem +\startitem + I could only do this because the \CONTEXT\ users are so tolerant. +\stopitem +\startitem + Some seem to constantly check for updates so they help with fast testing. +\stopitem +\startitem + The \CONTEXT\ code base gets stepwise adapted (split files) which again + forces users to test. +\stopitem +\startitem + It takes a lot of time because we take small steps in order not to mess up. +\stopitem +\startitem + I would not do it without the positive attribute of the \CONTEXT\ users. +\stopitem +\startitem + It's all about motivation and I thank the \CONTEXT\ users for providing this + friendly and non|-|competitive bubble! +\stopitem + +\stopitemize + +\starttitle[title=Todo] + +\startitemize + +\startitem + Maybe add some more sanity checks in order to catch errors intruded by + callbacks. Maybe add some more tracing too. +\stopitem +\startitem + Explore variants, like having registers in dedicated eqtb tables so that we + can allocate them dynamically (mostly for the fun of doing it). +\stopitem +\startitem + Add some more documentation (read: addition cq.\ remarks about where the + original documentation no longer applies, but we have years for doing that). +\stopitem +\startitem + Update the manual (which is done occasionally in batch based on print|-|outs; + there is no real need to hurry because we still experiment). +\stopitem +\startitem + Apply some of the new stuff in \LMTX. Take up some challenges. +\stopitem +\startitem + Wrap up new functionality (once it's stable) in articles and other documents. +\stopitem + +\stopitemize + +\stoptitle + +\starttitle[title=And \LUATEX ?] + +\startitemize + +\startitem + Of course \LUATEX\ will be maintained! After all, \MKIV\ needs it and it + serves as reference for the front|-|end rendering and back|-|end generation + when we're messing with \LUAMETATEX. +\stopitem +\startitem + It is used by \LATEX\ and there are now also plain inspired packages. Because + there are spin|-|offs (\LATEX\ has settled on a version with built|-|in font + processing) we cannot change much. +\stopitem +\startitem + And \LUATEX\ being nicely integrated into \TEXLIVE\ is another argument for + not touching it too much. +\stopitem +\startitem + I have no clue of \LUATEX\ usage but that fact alone already makes an + argument for being even more careful. It's bad advertisement for \TEX\ when + users who use the low level interfaces get confronted with conceptual + changes. +\stopitem +\startitem + So in the end not much will be back ported to \LUATEX: at some point the code + base became too different and it's the price paid for the stability demand. + That way we cannot introduce new bugs either. It also doesn't pay of. +\stopitem +\startitem + But, a few non|-|intrusive things might actually trickle into it in due time, + also out of self interest: it might help to share code between \MKIV\ and + \LMTX. +\stopitem + +\stopitemize + +\stopdocument |