MiniLaTeX

MiniLaTeX is a subset of LaTeX that can be rendered into pdf by standard tools such as pdflatex or into HTML by a suitable application, e.g., MiniLateX Demo or www.knode.io. For a technical discussion, see the Hackernoon article, Towards LaTeX in the Browser.

You can also experiment with MiniLaTeX using this Ellie.

Basics

Example. First, import MiniLatex

> import MiniLatex.Driver as MiniLatex

Second, make these definitions

> text = "\\begin{itemize}\n\\item Eggs\n\\item Milk\n\\item Bread\n\\end{itemize}"
> macroDefinitions = ""

Third, run MiniLatex.render;

> MiniLatex.render marcroDefinitions text

to get the HTML

"<p>\n \n<ul>\n <li class=\"item1\"> Eggs</li>\n <li class=\"item1\"> Milk</li>\n <li class=\"item1\"> Bread</li>\n\n</ul>\n\n</p>"
    : String

In this case, there are no macro definitions; the rendered text is

  <p>

  <ul>
   <li class="item1"> Eggs</li>
   <li class="item1"> Milk</li>
   <li class="item1"> Bread</li>

  </ul>

  </p>

API

If your applications simply renders strings of MiniLatex text to HTML, Driver.renderMiniLatex is all you need from this package. If you wish to do some kind of live editing on a piece of text, there is a another, slightly more complex method which involves the notion of an EditRecord. An EditorRecord keeps track of various types of information about the text being processed, e.g., a list of paragraphs and a list of rendered paragraphs. When the document is changed, then rendered, the update function figures out which paragraphs have changed, renders them, and updates the list of rendered paragraphs accordingly. Other optimizations for rendering equations by Mathjax require a "random" integer seed. Its role is explained in the documentation of the Differ module.

An edit record record can be set up using MiniLatex.setup.
It is generally stored in the application model, e.g.,

seed = 1234
model.editRecord = MiniLatex.setup seed text

At this point, editRecord contains a list of strings representing paragraphs of the text, and another list of strings representing those paragraphs rendered into HTML.

To extract the rendered text from the EditRecord, use

MiniLatex.getRenderedText macroDefinitions editRecord

Here macroDefinitions is a string representing macros that MathJax will use in rendering mathematical text. Here is an example:

"""
  $$
  \def\bbR{\mathbb{Z}}
  \def\caP{\mathcal{P}}
  \newcommand{\bra}{\langle}
  \newcommand{\ket}{\rangle}
  \newcommand{\set}[1]{\{#1\}}
  \newcommand{\sett}[2]{\{ #1 | #2 \}}
  $$
"""

Note that the definitions are enclosed in double dollar signs.

To update the EditRecord with modified text, use

MiniLatex.update seed editRecord text

The integer seed should be either chosen at random or given sequentially.

In applications which make use of an EditRecord stored in the model, you will need to initialize that data structure. For this use the 0-ary emptyEditRecord function, e.g., model.editRecord = emptyEditRecord.

Summary

To summarize, most work can be done with five points of contact with the MiniLatex API:

1. MiniLatex.render macroDefinitions text : String
2. MiniLatex.setup seed text : EditRecord
3. MiniLatex.getRenderedText macroDefs editRecord : String
4. MiniLatex.update seed editRecord text : EditRecord
5. MiniLatex.emptyEditRecord : EditRecord

The above assumes import MiniLatex.Driver as MiniLatex

Acknowledgments

I wish to acknowledge the generous help that I have received throughout this project from the community at http://elmlang.slack.com, with special thanks to Ilias van Peer (@ilias).