An overview of TeXmacs from altitude

Main features

• Visual structured editor: WYSWYG & WYSWYM

• Inspired by TeX and Emacs

• High-quality typesetting algorithms (including microtypography)

• Special features for mathematical typesetting and input

• Support for interactive sessions: Scheme, Python, R, Octave, Maxima, Axiom, Mathemagix (and other CAS).

• Multi-platform: Unix, MacOS, Windows (via Qt)

• Own format (XML like). Native output to PDF and PS. Export to LaTeX, HTML

• Internal image editor, interfaces to Svn and Git, versioning tool, database tool, encryption of documents.

• Website and documentation written in TeXmacs

Gallery

Development

• Started in 1998 by Joris Van Der Hoeven

  • v0.2.3β released 26 Oct 1999

  • v1.0 (2002)

  • Qt backend in v1.0.7 (2008)

  • native Pdf support in v1.99.1 (2013)

  • currently version 1.99.9 (soon 2.1)

• Written in C++ (~300.000 loc) and Scheme (~150.000 loc) (from [openhub]).

• Fully modular, external dependencies (mostly) isolated via tight interfaces.

• Two UI backends: legacy X11 with custom widget library, modern Qt backend (cross-platform support).

• GNU Guile as extension language. C++ export basic manipulation routines and few internal datatypes.

TeXmacs' content model

All TeXmacs documents or document fragments can be thought of as trees.

For instance, the tree

typically represents the formula

External representations

Serialization of TeXmacs documents without loss of informations

• TeXmacs format

  <with|mode|math|x+y+<frac|1|2>+<sqrt|y+z>>

• XML format

  <frac><tm-arg>1</tm-arg><tm-arg>2</tm-arg></frac>+<sqrt>y+z</sqrt>

• Scheme format

  (with "mode" "math" (concat "x+y+" (frac "1" "2") "+" (sqrt "y+z")))

Typesetting

Typesetting process converts TeXmacs trees into boxes:

The typesetting primitives are designed to be very fast and they are built-in into the editor:

The rendering of many of the primitives may be customized through the built-in environment variables.

The stylesheet language allows the user to write new primitives (macros) on top of the built-in primitives.

Macros

Evaluation of TeXmacs trees proceeds by reduction of the primitives, essentialy by evaluation of macro applications.

Macros have editable input fields. Examples here below (activate the macros):

<assign|hello|>

<assign|seq|>

Guile as extension language

TeXmacs is extendable and customizable in various ways:

• Guile embedded as extension and scripting language

• A plugin system allows asyncronous communication with external programs

• Mechanism to dynamically load external code (via C interface)

Guile is easy to embed and provides a reasonably fast implementation of Scheme.

Why Scheme?

1. Allows to mix programs and data in a common framework.

2. Allows to customize the language itself, by adding new programming constructs.

3. Allows to write programs on a very abstract level.

Menus

(menu-bind file-menu
  ("New" (new-buffer))
  ("Load" (choose-file load-buffer "Load file" ""))
  ("Save" (save-buffer))
  …)

can be easily extended from user code:

(menu-bind insert-menu
  (former)
  –––
  (-> "Opening"
      ("Dear Sir" (insert "Dear Sir,"))
      ("Dear Madam" (insert "Dear Madam,")))
  (-> "Closing"
      ("Yours sincerely" (insert "Yours sincerely,"))
      ("Greetings" (insert "Greetings,"))))

Some more GUI

Keybindings

(kbd-map
  ("D e f ." (make 'definition))
  ("L e m ." (make 'lemma))
  ("P r o p ." (make 'proposition))
  ("T h ." (make 'theorem)))

The file my-init-buffer.scm is executed every time a buffer is loaded, it allows some specific customizations. For example:

(if (not (buffer-has-name? (current-buffer)))
    (begin
      (init-style "article")
      (buffer-pretend-saved (current-buffer))))

(if (not (buffer-has-name? (current-buffer)))
    (make-session "maxima" (url->string (current-buffer))))

Scheme invocation

Scheme commands can be invoked interactively (like in Emacs) using the Meta+X shortcut.

A Scheme session is started using the Insert→Session→Scheme menu item:

Scheme commands can be invoked from the command line:

texmacs text.tm -x "(print)" -q

Or scheme statement executed from inside TeXmacs macros:

The tm-define macro

Contextual overloading

Function definition can depend on several run-time conditions (e.g. editor mode). This allows to develop modular user interfaces.

(tm-define (hello) (insert "Hello"))
(tm-define (hello) (:require (in-math?)) (insert-go-to "hello()" '(6)))

(tm-define (hello)
  (if (in-math?) (insert-go-to "hello()" '(6)) (former)))

(tm-define (my-replace what by)
  default-implementation)

(tm-define (my-replace what by)
  (:require (== what by))
  (noop))

Meta informations

(tm-define (square x)
  (:synopsis "Compute the square of @x")
  (:argument x "A number")
  (:returns "The square of @x")
  (* x x))

Used via e.g. (help square). Allows for interactive input of parameters: typing Meta+Shift+X followed by square and Return and you will be prompted for “A number” on the footer (or in a dialog). Tab-completion.

(tm-property (choose-file fun text type)
  (:interactive #t))

to indicate interactive commands in menu items like:

("Load" (choose-file load-buffer "Load file" ""))

Check-marks for menu items:

(tm-define (toggle-session-math-input)
  (:check-mark "v" session-math-input?)
  (session-use-math-input (not (session-math-input?))))

(tm-define mouse-unfold
  (:secure #t)
  (with-action t
    (tree-go-to t :start)
    (fold)))

Scheme representation TeXmacs content

• Passive trees (stree)

  

  is typically represented by

  (frac (concat "a" (rsup "2")) "b+c")

  convenient to manipulate content directly using standard Scheme routines on lists.

• Active trees (tree). TeXmacs internal C++ type tree which is exported to Scheme via the glue. Keeps track of the position of the tree inside the global document tree and can be used to programmatically modify documents.

• Hybrid representation (content). an expression of the type content is either a string, a tree or a list whose first element is a symbol and whose remaining elements are other expressions of type content.

  scheme]

  (tree-set! t '(document "First line." "Second line."))

  scheme]

  (tree-set t 1 "New second line.")

  scheme]

  (tree-set t 0 ‘(strong ,(tree-ref t 0)))

A full example

(tm-define (swap-numerator-denominator t)
  (:require (tree-is? t 'frac))
  (with p (tree-cursor-path t)
    (tree-set! t ‘(frac ,(tree-ref t 1) ,(tree-ref t 0)))
    (tree-go-to t (cons (- 1 (car p)) (cdr p)))
    (tree-focus t)))

To be called as (swap-numerator-denominator (focus-tree)), or just add it as a structured variant to frac

(tm-define (variant-circulate t forward?)
  (:require (tree-is? t 'frac))
  (swap-numerator-denominator t))

Regular expressions

TeXmacs implements the routines match? and select for matching regular expressions and selecting subexpressions along a “path”. For instance: in the current buffer search all expressions of the form

where and are general expressions:

More scheme

User preferences

(define-preferences
  ("Gnu's hair color" "brown" notify-gnu-hair-change)
  ("Snail's cruising speed" "1mm/sec" notify-Achilles))

New data formats and converters

(define-format blablah
  (:name "Blablah")
  (:suffix "bla"))

(converter blablah-file latex-file
  (:require (url-exists-in-path? "bla2tex"))
  (:shell "bla2tex" from ">" to))

When a format can be converted from or into TeXmacs, then it will automatically appear into the File→Export and File→Import menus. Similarly, when a format can be converted to Postscript, then it also becomes a valid format for images. TeXmacs also attempts to combine explicitly declared converters into new ones.

Dialogues & Widgets

Dialogues

Widgets

tree-view

Forms

Bibliography styles

New styles can be defined via Scheme modules like example.scm defined as follows:

(texmacs-module (bibtex example)
  (:use (bibtex bib-utils)))

(bib-define-style "example" "plain")

(tm-define (bib-format-date e)
  (:mode bib-example?)
  (bib-format-field e "year"))

This example style behaves in a similar way as the plain style, except that all dates are formatted according to our custom routine. Styles are stored in $TEXMACS_PATH/progs/bibtex and referred to as e.g. tm-example (for when used in a TeXmacs document.

Graphics

Graphics objects are also part of the TeXmacs format and can be manipulated programmatically from Scheme.

Actually, part of the graphics editor is written in Scheme.

The future of TeXmacs

Many improvements ahead

• Version 2.1 to be released soon

• Update the backend to Qt 5 (currently Qt 4.8) [almost there]

• Adapt the scheme code to run on Guile 3. (currently Guile 1.8) [WIP]

• New website, documentations, videos [WIP]

• Jupyter plugins (protocol to interface to many computational kernels, e.g. Python, Julia, R, Haskell, Guile, ...)

• Improvements to the styling of presentations and posters [WIP]

• More documentation, more tutorial, grow community [Stackexchange proposal]

• Collaboration tools

• Bibliography management with Zotero

Hacking TeXmacs

Many opportunities for contributions for all tastes

• From the outside

  • Write and review documentations, tutorials, videos, improve community, advertise

  • Develop plugins to your preferred system or to add your preferred feature, e.g.: literate programming tools with beautyful output

  • Write new document styles, templates, presentation styles, poster styles

  • Font tuning

• Hack the C++ code

  • Understand the code and write developer documentation

  • Improve the Qt backend, fix bugs, add features, improve stability, better image handling and PDF export of TeXmacs features

  • Write new backends (Cocoa), port to tablets or to the browser

• Hack Scheme

  • Help porting to Guile 3, improve speed

  • fix bugs, review code, add new cool features