Pandoc based J Syntax Highlighting

John MacFarlane’s excellent command line utility Pandoc is a Haskell program that converts to and from various text markup languages. Pandoc’s help option lists its supported input and output formats.

The following examples are Linux bash shell commands. Windows shell commands are identical.

$ pandoc --help
pandoc [OPTIONS] [FILES]
Input formats:  native, json, markdown, markdown+lhs, rst, rst+lhs, docbook,
                textile, html, latex, latex+lhs
Output formats: native, json, html, html5, html+lhs, html5+lhs, s5, slidy,
                slideous, dzslides, docbook, opendocument, latex, latex+lhs,
                beamer, beamer+lhs, context, texinfo, man, markdown,
                markdown+lhs, plain, rst, rst+lhs, mediawiki, textile, rtf, org,
                asciidoc, odt, docx, epub

Some Pandoc conversions are better than others. Pandoc does a better job of turning markdown into LaTeX than LaTeX into markdown. It’s also better at converting HTML into LaTeX than LaTeX into HTML. Pandoc works best when converting markdown, the simplest of its inputs, to other formats. In fact Pandoc does such a good job of converting markdown to HTML, HTML+MathJax, LaTeX or PDF that many writers are now saving their source documents as markdown text knowing they can easily produce other formats as needed.

As handy as Pandoc’s markup conversions are this nifty tool also supports syntax highlighting for over a hundred programming languages. Unfortunately, my favorite language J is not on Pandoc’s list of highlighted languages. [1] Where have I run into this problem before? Luckily for me Pandoc is an open source tool and Pandoc’s author has made it easy to add new highlight languages.

Pandoc is a Haskell program. I’ve been aware of Haskell’s existence for years but until I decided to take on this specialized Pandoc hack I had never studied or used the language. Usually when you set out to modify a large program in an unfamiliar programming language you’re in for what can only be described as an f’ing educational experience. It’s a testament to the quality of the Haskell’s global libraries and standard tools that a complete Haskell novice can effectively tweak large Haskell programs. Here’s what you have to do.

  1. Install the Haskell Platform. The Haskell Platform is available for all the usual suspects. I’ve used both the Windows and Linux versions. I almost installed the Mac version on my wife’s Mac but resisted the urge.
  2. Get with the Cabal. Cabal is the main Haskell package distribution and build utility. Cabal comes with the Haskell Platform and is easily accessed from the command line. Type cabal --help in your favorite shell to view the program’s options.
  3. Spend sometime playing with Hackage. Hackage contains a large set of Haskell packages including all the source code required to build Pandoc.

After installing the Haskell Platform and familiarizing yourself with Cabal try building Pandoc. This will thoroughly exercise your Haskell system. Instructions for building Haskell packages are here. After reading the package build instructions run the following in your command shell:

$ cabal update
$ cabal install pandoc

This will download, compile and install a number of Haskell packages. Where Cabal puts the packages depends on your operating system. Cabal saves Linux packages in a hidden local directory. On my machine they ended up in:

/home/john/.cabal/lib

If you managed to build Pandoc you’re now ready to add a new highlighting language. Pandoc uses the highlighting-kate package for highlighting. highlighting-kate works by reading a directory of Kate editor xml language regex based definition files and generating custom language parsers. We want to generate a custom J parser so we need to download highlighting-kate source and add a Kate xml definition file for J.

You can find such a J Kate file on the J Wiki here. Download this file by cutting and pasting and save it as j.xml. Now do the following.

  1. Run the Pandoc version command pandoc --version of the Pandoc you just built to determine the version of the highlighting-kate package you need.
  2. Use Cabal to unpack the required highlighting-kate package. This downloads the required package and creates a temporary subdirectory in your current directory that contains package source code.
    $ cabal unpack highlighting-kate-0.5.3.2
    Unpacking to highlighting-kate-0.5.3.2/
  3. Move into the temporary subdirectory and copy the Kate j.xml file to the package’s xml subdirectory.
    $ cd highlighting-kate-0.5.3.2
    $ cp ~/pd/blog/j.xml ~/temp/highlighting-kate-0.5.3.2/xml/j.xml
  4. Configure the package.
    $ cabal configure
    Resolving dependencies...
    Configuring highlighting-kate-0.5.3.2...
  5. Build the highlighting-kate package.
    $ cabal build
    Resolving dependencies...
        ... (omitted) ...
  6. If highlighting-kate builds without problems run the command.
    $ runhaskell ParseSyntaxFiles.hs xml
    Writing Text/Highlighting/Kate/Syntax/SqlPostgresql.hs
    Writing Text/Highlighting/Kate/Syntax/Scala.hs
        ... (omitted) ...

    ParseSyntaxFiles scans the package’s xml subdirectory and generates language specific parsers. If all goes well you will find J.hs in this directory.

    ~/temp/highlighting-kate-0.5.3.2/Text/Highlighting/Kate/Syntax

    J.hs, like all the files referred to in this post, are available in the files sidebar in the Haskell/Pandoc subdirectory.

  7. Now rebuild the highlighting-kate package. This compiles your new J.hs parser file.
    $ cabal build
    Resolving dependencies...
        ... (omitted) ...
  8. After rebuilding the package run the Cabal copy command to put the modified package in the expected library location.
    $ cabal copy
    Installing library in
    /home/john/.cabal/lib/highlighting-kate-0.5.3.2/ghc-7.4.1

Now that the highlighting library is up to date we have to rebuild Pandoc. To do this mirror the steps taken to download and build the highlighting package.

  1. Use Cabal to unpack the Pandoc package.
    $ cd ~/temp
    $ cabal unpack pandoc-1.9.4.2
    Unpacking to pandoc-1.9.4.2/
  2. Switch to the Pandoc subdirectory and configure the package.
    $ cabal configure
    Resolving dependencies...
    [1 of 1] Compiling Main      ( Setup.hs, dist/setup/Main.o )
        ... (omitted) ...
  3. Rebuild Pandoc.
    $ cabal build 
    Building pandoc-1.9.4.2...
    Preprocessing executable 'pandoc' for pandoc-1.9.4.2...
        ... (omitted) ...

    If all goes well a Pandoc executable will be written to this subdirectory.

    ~/temp/pandoc-1.9.4.2/dist/build/pandoc
  4. You can check the new executable by running pandoc --version. The result should display J in the list of supported languages.

Now that we have a Pandoc that can highlight J we’re almost ready to blog gaudy J code. However before doing this we need to install some custom CSS. Custom CSS is not available on free WordPress.com blogs. To apply custom coloring schemes get the custom package and learn how to use WordPress’s custom CSS editor. As daunting as this sounds it’s no problemo for my limited purposes. To enable tango style Pandoc syntax highlighting on your WordPress blog paste tango.css into the custom CSS editor, check the “Add my CSS to CSS stylesheet” button and then press the “Save Stylesheet” button. Now your WordPress blog will be sensitive to the HTML span tags generated by Pandoc.

To show that all this hacking works as intended you can check out the Pandoc generated versions of this blog post. I’ve posted the original markdown source with PDF, LaTeX and HTML versions. All these files are available via the files sidebar. You can generate the HTML version with the command:

$ pandoc -s --highlight-style=tango PJHighlight.markdown -o PJHighlight.html

To get other versions simply change the file extension of the output -o file.

Bonebridge puzzle in MYST IV

Bonebridge puzzle in MYST IV
Click for “Haven Age” Walkthrough

Finally we are ready to post syntax highlighted J code. The following J verb bonebridge generates all “likely” lock combinations for the MYST IV Bonebridge puzzle in Pandoc’s tango style. At one time I was a big fan of MYST computer games. I always enjoyed being lost in a beautiful puzzle which, if you discard the beautiful bit, is a pretty accurate description of my programmer day job.

bonebridge=:3 : 0

NB.*bonebridge  v--  lists  totem  symbol  permutations for  bone
NB. bridge.
NB.
NB. The  solution to  this MYST IV puzzle is similiar to the book
NB. shelf puzzle in Tomanha but requires far more  exploration of
NB. the age.
NB.
NB. You are confronted with  5  bones on the lock.  All the bones
NB. move independently. You can see the settings for 4 bones. One
NB. bone  has a  broken display.  The four  visible bones  have 8
NB. symbols on them in the  same order.  The  5th bone also has 8
NB. symbols and you can "safely" infer they are in the same order
NB. as the visible bones.
NB.
NB. Four  bone  symbols   match  symbols  found  on  totem  poles
NB. distributed around the  age. There is a  5th  totem pole  but
NB. fruit eating mangrees  obscure  the  totem symbol and  I have
NB. never  seen it.  The  totem  poles are  associated  with  age
NB. animals. In addition to the totem poles  there is  a chart in
NB. the  mangree  observation  hut  that  displays  a  triangular
NB. pattern  of paw  prints.  The  paw  prints  define an  animal
NB. ordering. The order  seems to be how  dangerous a  particular
NB. animal is;  big scary animals  are at the top and vegetarians
NB. are at the bottom.
NB.
NB. Putting the clues together you infer:
NB.
NB. a)  the  bridge  combination  is  some  permutation  of  five
NB. different symbols
NB.
NB. b) two possible symbol orders are given by the paw chart
NB.
NB. c) you know 5 symbols and the 4th is one of the remaining 4
NB.
NB. If this is  the  case  the number of  possible  lock settings
NB. shrinks from 32768 to the ones listed by this verb.
NB.
NB. monad:  bonebridge uuIgnore
NB.
NB.   bonebridge 0

NB. known in paw order
known=.    s: ' square triangle hourglass yingyang'
unknown=.  s: ' clover cross xx yy'

NB. all possible lock permutations
settings=. ~. 5 {."1 tapl known,unknown
assert. ((!8)%!8-5) = #settings

NB. possible ordering - we don't know
NB. what the fifth symbol is but it
NB. occurs in the 3rd slot
order=. 8#s:<''
order=. known (0 1 6 7)} order
order=. unknown (2 3 4 5)} order

NB. keep unknown only in 3rd slot
settings=. settings #~ -. +./"1 (0 1 3 4{"1 settings) e. unknown
settings=. settings #~ (2 {"1 settings) e. unknown

NB. strict row sequence adverb
srsm=.  1 : '*./"1 u/&> 2 <\"1 y'

NB. retain strictly increasing and strictly decreasing rows
grade=. order i. settings
settings #~ ((< srsm)"1 grade) +. (> srsm)"1 grade
)

[1] J has its own syntax highlighting tools but they are not part of a document generation system. Pandoc’s highlighters elegantly feed into many output formats making them far more useful.

WordPress to LaTeX with Pandoc and J: Using TeXfrWpxml.ijs (Part 3)

WordPress to LaTeX

WordPress to LaTeX

In this post I will describe how to use the J script TeXfrWpxml.ijs to generate LaTeX source from WordPress export XML.  I am assuming you have worked through (Part 1) and (Part 2) and have:

  1. Successfully installed and tested Pandoc.
  2. Installed and tested a version of J.
  3. Set up appropriate directories (Part 2).
  4. Know how to use LaTeX.

Item #4 is a big if.  Inexperienced LaTeX users will probably not enjoy a lot of success with this procedure as the source generated by TeXfrWpxml.ijs requires manual edits to produce good results.  However, if you’re not a LaTeX guru, do not get discouraged. It’s not difficult to create blog documents like bm.pdf.

Step 1: download WordPress Export XML

How to download WordPress export XML is described here.  Basically you go to your blog’s dashboard, select Tools, choose Export  and select the All content option.

Tools > Export > All Content

Tools > Export > All Content

When you press the Download Export File  button your browser will download a single XML file that contains all your posts and comments. Remember where you save this file. I put my export XML here.

c:/pd/blog/wordpress/analyzethedatanotthedrivel.wordpress.xml

Step 2: download TeXfrWpxml.ijs

Download TeXfrWpxml.ijs and remember where you save it.  I put this script here.

c:/pd/blog/TeXfrWpxml.ijs

Step 3: start J and load TeXfrWpxml.ijs

TeXfrWpxml.ijs was generated from JOD dictionaries. With JOD it’s easy to capture root word dependencies and produce complete standalone scripts. TeXfrWpxml.ijs needs only the standard J load profile to run.  It does not require any libraries or external references and should run on all Windows and Linux versions of J after 6.01.  Loading this script is a simple matter of executing:

load 'c:/pd/blog/TeXfrWpxml.ijs'

The following shows this script running in a J 7.01 console. The console is the most stripped down J runtime.

Step 4: review directories and necessary LaTeX files

The conversion script assumes proper directories are available up: see Part 2. The first time you run TeXfrWpxml.ijs it’s a good idea to check that the directories and files the script is expecting are the ones you want to process.  You can verify the settings by displaying TEXFRWPDIR, TEXINCLUSIONS, TEXROOTFILE and TEXPREAMBLE.

  TEXPREAMBLE
bmamble.tex
  TEXFRWPDIR
c:/pd/blog/wp2latex/
  TEXINCLUSIONS
inclusions
  TEXROOTFILE
bm.tex
  TEXPREAMBLE
bmamble.tex

If all these directories and files exist go to step (5).

Step 5: make sure you are online

The first time you run the converter it will attempt to download all the images referenced in your blog. This is where wget.exe gets executed.  Obviously to download anything you must be connected to the Internet.

Step 6: run LatexFrWordpress

Run the verb LatexFrWordpress.  The monadic version of this verb takes a single argument: the complete path and file name of the export XML file you downloaded in step (1).

xml=: 'c:/pd/blog/wordpress/analyzethedatanotthedrivel.wordpress.xml'

LatexFrWordpress xml

As the verb runs you will see output like:

   LatexFrWordpress xml
What's In it for Facebook?
downloading: c:/pd/blog/wp2latex/inclusions/demotivational-posters-facebook-you.jpg
1 downloaded; 0 not downloaded; 0 skipped
Fake Programming
downloading: c:/pd/blog/wp2latex/inclusions/672169130_vajvn-M.png
1 downloaded; 0 not downloaded; 0 skipped
Laws or Suggestions
downloading: c:/pd/blog/wp2latex/inclusions/i-B5mfdRF-M.jpg
1 downloaded; 0 not downloaded; 0 skipped
Lens Lust

... many lines omitted ...

downloading: c:/pd/blog/wp2latex/inclusions/i-mNK4RHL-M.png
1 downloaded; 0 not downloaded; 0 skipped
WordPress to LaTeX with Pandoc and J: LaTeX Directories (Part 2)
0 downloaded; 0 not downloaded; 1 skipped
+-++
|1||
+-++

When the verb terminates you should have a directory c:/pd/blog/wp2latex full of *.tex files:  one file for each blog post. Now the hard work starts.

Step 7: editing LaTeX posts

The conversion from WordPress XML to LaTeX produces files that require manual edits. The more images, video, tables and other elements in your posts the more demanding these edits will become.  My blog has about one image per post.  Most of these images are wrapped by text. LaTeX has a mind of its own when it comes to floating figures and getting illustrations to behave requires far more parameter tweaking than it should. This is a longstanding weakness of LaTeX that pretty much everyone bitches about. My advice is start at the front of your document and work through it post by post. The files generated by LatexFrWordpress do not attempt to place figures for you but they do bolt in ready-made figure templates as comments that you can experiment with.  Each post file is also set up for separate LaTeX compilation. You don’t have to compile your entire blog to tweak one post. The one good thing about this edit step is once you have sorted out your old posts you do not have to revisit them unless you make major global document changes. The next time you run LatexFrWordpress it will only bring down new posts and images.

Step 8: compile your LaTeX blog

I use batch files and shell scripts to drive LaTeX compilations.  I processed my blog with this batch file.

echo off
rem process blog posting (bm.tex) root file
title Running Blog Master/LaTeX ...

rem first pass for aux file needed by bibtex
lualatex bm

rem generate/reset bbl file
bibtex bm
makeindex bm

rem resolve all internal references - may
rem comment out when debugging entire document
lualatex bm
lualatex bm

rem display pdf - point to prefered PDF reader
title Blog Master/LaTeX complete displaying PDF ...
"C:\Program Files\SumatraPDF\SumatraPDF.exe" bm.pdf

The presence of Unicode APL, see this post, forced me to use lualatex. I needed some very nonstandard APL fonts.  See bm.pdf — also available on the Download this Blog page — to judge the effectiveness of my edits. Producing nice figure laden typeset blog documents is work but, as I will describe in the next post, producing image free eBooks is a simple and far less laborious variation on this process.

WordPress to LaTeX with Pandoc and J: LaTeX Directories (Part 2)

WordPress to LaTeX

WordPress to LaTeX

In this post I will describe the LaTeX directory structure the J script TeXfrWpxml.ijs is expecting. To convert WordPress export XML to LaTeX with this script you will have to set up similar directories.

LaTeX documents are built from *.tex[1] files. This makes LaTeX more like a compiled programming language than a word processing program. There are advantages and disadvantages to the LaTeX way. In LaTeX’s favor, the system is enormously adaptable, versatile and powerful. There is very little that LaTeX/TeX and associates cannot do.  Unfortunately, “with great power comes great responsibility.” LaTeX is demanding! You have to study LaTeX like any other programming language. It’s not for everyone but for experienced users it’s the best way to produce documents with the highest typographic standards.

LaTeX directory structure

To use LaTeX efficiently it’s wise to pick a document directory structure and stick with it. I use a simple directory layout. Each document has a root directory. The root directory used by TeXfrWpxml.ijs is:

Windows c:/pd/blog/wp2latex
Linux /home/john/pd/blog/wp2latex

I put my document specific *.tex, *.bib, *.sty and other LaTeX/TeX files in the root. To handle graphics I create an immediate subdirectory called inclusions.

c:/pd/blog/wp2latex/inclusions

The inclusions directory holds the document’s *.png, *.jpg, *.pdf, *.eps and other graphics files.  To reference files in the inclusions directory with the standard LaTeX graphicx package insert

\usepackage{color,graphicx,subfigure,sidecap}
\graphicspath{{./inclusions/}}

in your preamble. Finally, to track document changes I create a GIT repository in the root directory.

c:/pd/blog/wp2latex/.git

Self contained directories

I take care to keep my document directories self-contained. Zipping up the root and inclusions directory collects all the document’s files. This means that I sometimes have to copy files that are used in more than one document. Many LaTeX users maintain a common directory for such files but I’ve found that common directories complicate moving documents around. You’re always forgetting something in the damn common directory or you are copying a buttload of mostly irrelevant files from one big confusing common directory to another.

TeXfrWpxml.ijs files

The TeXfrWpxml.ijs script searches for these files in the root directory.

bm.tex Main LaTeX root file
bmamble.tex LaTeX preamble

bm.tex references bmtitlepage.tex.  I prefer a separate title page file; simply comment out this file if you create titles in other ways. The zip file wp2latex.zip contains a test directory in the format expected by TeXfrWpxml.ijs.  It also has a subset of my blog posts already converted to LaTeX. To get ready for WordPress to LaTeX with Pandoc and J: Using TeXfrWpxml.ijs (Part 3) download wp2latex.zip and attempt to compile bm.tex.  You might have to download a number of LaTeX packages.  Once you have successfully compiled bm.tex you are ready for the next step.


[1] LaTeX uses many other file types but key files are usually *.tex files.

WordPress to LaTeX with Pandoc and J: Prerequisites (Part 1)

There are no quick WordPress to LaTeX fixes

WordPress to LaTeX

WordPress to LaTeX

Over the next three posts I will describe how to convert WordPress’s export XML to LaTeX source code.  I know that many of you are looking for a quick WordPress to LaTeX fix; unfortunately there are no quick fixes. The two formats come from different worlds and are used in different ways.  Producing useful LaTeX source from WordPress export XML will require manual edits.  My goal here is to minimize manual edits, produce high quality LaTeX source and to outline what you will have to contend with. To get an idea of what you can expect download the LaTeX compiled version of this post.

Visual and Logical composition

WordPress and LaTeX are examples of the two basic approaches, visual and logical, taken by writing software.  Visual systems value appearance. It matters what things look like and no effort is spared to get the right look. Logical systems value content. What’s said is far more important than what it looks like. Logical systems impose order and structure and typically defer visual elements.  As you might expect there is no such thing as a pure visual or logical writing system. Successful systems use both approaches to a greater or lesser degree. Composing WordPress blog posts is roughly 35% visual and 65% logical.[1]  LaTeX composition is about 10% visual and 90% logical. The numbers do not line up; there is a basic mismatch here.

Many format X to LaTeX converters tackle this mismatch by attempting to maintain visual fidelity. This is a catastrophic error that renders the entire conversion useless.  Here’s a hint. If you’re using a predominantly logical system like LaTeX you don’t give a rodent’s posterior about visual fidelity. This method dispenses with all but the most basic of visual elements. No attempt is made to preserve fonts, type sizes, image scale, justification, hyphenation, text color and so forth.  The goal is to produce working LaTeX source that can be transformed to whatever final layout the author desires.

Prerequisite Software

I use two programs to transform WordPress export XML to LaTeX:  the J programming language and John MacFarlane’s Pandoc.  Pandoc is an excellent text mark-up to mark-up converter.  It wisely avoids attempting to convert entire complex documents and focuses on getting parts of documents right.  It does a particularly good job of converting HTML to LaTeX which is a crucial part of this process.  I use Pandoc to transform the HTML embedded in WordPress export XML CDATA elements to *.tex files and I use J to preprocess and post process Pandoc inputs and outputs and to stitch everything together into a set of LaTeX ready files.

Download Pandoc from here. I use the Windows command line version. There are Linux and Mac versions as well. Download J from here.  The easiest J install is the 32 bit Windows J 6.02 version. Other versions require additional steps to configure and deploy. If you are already a J user there is no need to install a particular system but you will need:

  1. The task library require 'task'
  2. The utility program wget.exe

Both of these components are typically part of the J distribution.

Install and check prerequisites

To continue download and install Pandoc and J and run the following tests; if you succeed you’re system is ready for WordPress to LaTeX with Pandoc and J: LaTeX Directories (Part 2).

Pandoc Test:

Download the test file: cdata.html and run Pandoc from the command line:

pandoc –o cdata.tex cdata.html

cdata.html is an example of the HTML code you find in WordPress export XML CDATA elements.  Note: required files are also available in the files sidebar in the WordPress to LaTeX directory.

J Test:

Start a J session and enter the following commands:

require 'task'

shell 'wget –help'

shell 'wget http://conceptcontrol.smugmug.com/photos/i-mNK4RHL/0/L/i-mNK4RHL-L.png'

If the shell command is properly loaded and wget.exe is found you will see help text. The second shell command downloads an image file.  Downloading post images is part of the overall conversion process.


[1] Actually this is not bad. Page layout systems are far worse. A typical layout system might be 90% visual and 10% logical making layout systems polar opposites of LaTeX.

Typesetting UTF8 APL code with the LaTeX lstlisting package

UTF8 APL characters within a LaTeX lstlisting environment. Click for *.tex source code

Typesetting APL source code has always been a pain in the ass! In the dark ages, (the 1970’s), you had to fiddle with APL type-balls and live without luxuries like lower case letters. With the advent of general outline fonts it became technically possible to render APL glyphs on standard display devices provided you:

  1. Designed your own APL font.
  2. Mapped the atomic vector of your APL to whatever encoding your font demanded.
  3. Wrote WSFULL‘s of junk transliteration functions to dump your APL objects as font encoded text.

It’s a testament to either the talent, or pig headedness of APL programmers, that many actually did this. We all hated it! We still hate it! But, like an abused spouse, we kept going back for more.  It’s our fault; if we loved APL more it would stop hitting us!

When Unicode appeared APL’ers cheered — our long ASCII nightmare was ending. The more politically astute worked to include the APL characters in the Unicode standard. Hey if Klingon is there why not APL? Everyone thought it was just a matter of time until APL vendors abandoned their nonstandard atomic vectors and fully embraced Unicode. With a few notable exceptions we are still waiting. While we wait the problem of typesetting APL source code festers.

My preferred source code listing tool is the \LaTeX lstlisting package. lstlisting works well for standard ANSI source code.  I use it for J, C#, SQL, C, XML, Ocaml, Mathematica, F#, shell scripts and \LaTeX source code, i.e. everything except APL! lstlisting is an eight bit package; it will not handle arbitrary Unicode out of the box.  I didn’t know how to get around this so I handled APL by enclosing UTF8 APL text in plain \begin{verbatim} … \end{verbatim} environments. This works for XeLaTeX and LuaLaTeX but you lose all the lstlisting goodies. Then I saw an interesting tex.stackexchange.com posting about The ‘listings’ package and UTF-8. One solution to the post’s “French ligature problem” showed how to force Unicode down lstlisting‘s throat. I wondered if the same method would work for APL. It turns out that it does!

If you insert the following snippet of TeX code in your document preamble LuaLaTeX and XeLaTeX will properly process UTF8 APL text in lstlisting environments. You will need to download and install the APL385 Unicode font if it’s not on your system.  A test \LaTeX document illustrating this hack is available here. The compiled PDF is available here. As always these files can be accessed in the files sidebar.

% set lstlisting to accept UTF8 APL text
\makeatletter
\lst@InputCatcodes
\def\lst@DefEC{%
 \lst@CCECUse \lst@ProcessLetter
  ^^80^^81^^82^^83^^84^^85^^86^^87^^88^^89^^8a^^8b^^8c^^8d^^8e^^8f%
  ^^90^^91^^92^^93^^94^^95^^96^^97^^98^^99^^9a^^9b^^9c^^9d^^9e^^9f%
  ^^a0^^a1^^a2^^a3^^a4^^a5^^a6^^a7^^a8^^a9^^aa^^ab^^ac^^ad^^ae^^af%
  ^^b0^^b1^^b2^^b3^^b4^^b5^^b6^^b7^^b8^^b9^^ba^^bb^^bc^^bd^^be^^bf%
  ^^c0^^c1^^c2^^c3^^c4^^c5^^c6^^c7^^c8^^c9^^ca^^cb^^cc^^cd^^ce^^cf%
  ^^d0^^d1^^d2^^d3^^d4^^d5^^d6^^d7^^d8^^d9^^da^^db^^dc^^dd^^de^^df%
  ^^e0^^e1^^e2^^e3^^e4^^e5^^e6^^e7^^e8^^e9^^ea^^eb^^ec^^ed^^ee^^ef%
  ^^f0^^f1^^f2^^f3^^f4^^f5^^f6^^f7^^f8^^f9^^fa^^fb^^fc^^fd^^fe^^ff%
  ^^^^20ac^^^^0153^^^^0152%
  ^^^^20a7^^^^2190^^^^2191^^^^2192^^^^2193^^^^2206^^^^2207^^^^220a%
  ^^^^2218^^^^2228^^^^2229^^^^222a^^^^2235^^^^223c^^^^2260^^^^2261%
  ^^^^2262^^^^2264^^^^2265^^^^2282^^^^2283^^^^2296^^^^22a2^^^^22a3%
  ^^^^22a4^^^^22a5^^^^22c4^^^^2308^^^^230a^^^^2336^^^^2337^^^^2339%
  ^^^^233b^^^^233d^^^^233f^^^^2340^^^^2342^^^^2347^^^^2348^^^^2349%
  ^^^^234b^^^^234e^^^^2350^^^^2352^^^^2355^^^^2357^^^^2359^^^^235d%
  ^^^^235e^^^^235f^^^^2361^^^^2362^^^^2363^^^^2364^^^^2365^^^^2368%
  ^^^^236a^^^^236b^^^^236c^^^^2371^^^^2372^^^^2373^^^^2374^^^^2375%
  ^^^^2377^^^^2378^^^^237a^^^^2395^^^^25af^^^^25ca^^^^25cb%
  ^^00}
\lst@RestoreCatcodes
\makeatother

More on Kindle Oriented LaTeX

I’ve been compiling \LaTeX PDFs for the Kindle. If you like \LaTeX typefaces, especially mathematical fonts, you’ll love how they render on the Kindle. It’s a good thing because you won’t like the Kindle’s cramped page dimensions. For simple flow-able text this isn’t a big deal but for complex \LaTeX documents it is!

There are two basic \LaTeX \Longrightarrow Kindle  workflows.

  1. Convert your \LaTeX to HTML and then convert the HTML to mobi.
  2. Compile your \LaTeX for Kindle page dimensions.

For simple math and figure free documents mobi is the best choice because it’s a native Kindle format. You will be able to re-flow text and change font sizes on the fly. There are many \LaTeX to HTML converters. This is a good summary of your options. You can also find a variety of HTML to mobi converters. I’ve used Auto Kindle; it’s slow but produces decent results.

Compiling \LaTeX for Kindle page dimensions is more work. First decide what works best for your document: landscape or portrait. Portrait is the Kindle default but I’ve found that landscape is better for math and figure rich documents. You can flip back and forth between landscape and portrait on the Kindle but it will not re-paginate PDFs. Of course with mobi this is no problemo!

After choosing a basic layout expunge all hard-coded lengths from your source *.tex files. Replace all fixed lengths with relative page lengths. For example, 4in might become 0.75\textwidth. If you have hundreds of figures and images to adjust write a little program to replace fixed lengths. I did this while preparing a Kindle version of Hilbert’s Foundations of Geometry.

The next hurdle to overcome is the Kindle’s blase attitude about length units. \LaTeX is extremely precise: an inch is an inch to six decimals. This is not the case on the Kindle! You will have to load your PDFs on the Kindle and inspect margins for text overflows. Be prepared for a few rounds of page dimension tweaking! For more details about preparing \LaTeX source check out LaTeX Options for Kindle.

Finally, after you have compiled your PDF and loaded it on your Kindle, there are some Kindle options you should set to optimize your PDF reading experience. My next post will walk you through setting these options.

The following *.tex file loads packages that are useful for Kindle sizing. It also shows how to print out \LaTeX dimensions with the printlen package.

% A simple test document that displays some packages and settings
% that are useful when compiling LaTeXe documents for the Kindle.
% Compile with pdflatex or xelatex.
%
% Tested on MikTeX 2.9
% July 22, 2011

\documentclass[12pt]{article}

% included graphics in immediate subdirectory
\usepackage{graphicx}
\graphicspath{{./image/}}

% extended coloring
\usepackage[usenames,dvipsnames]{color}

% hyperref link colors are chosen to display
% well on Kindle monochrome devices
\usepackage[colorlinks, linkcolor=OliveGreen, urlcolor=blue,
            pdfauthor={your name}, pdftitle={your title},
            pdfsubject={your subject},
            pdfcreator={MikTeX+LaTeXe with hyperref package},
            pdfkeywords={your,key,words},
            ]{hyperref}

\usepackage{breqn}         % automatic equation breaking
\usepackage{microtype}     % microtypography, reduces hyphenation

% kindle page geometry (no page numbers)
%\usepackage[papersize={3.6in,4.8in},hmargin=0.1in,vmargin={0.1in,0.1in}]{geometry}

% portrait kindle page geometry space reserved for page numbers
\usepackage[papersize={3.6in,4.8in},hmargin=0.1in,vmargin={0.1in,0.255in}]{geometry}

% landscape geometry
%\usepackage[papersize={4.8in,3.6in},hmargin={0.1in,0.18},vmargin={0.1in,0.255in}]{geometry}

% headers and footers
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhead{}            % clear page header
\fancyfoot{}            % clear page footer

\setlength{\abovecaptionskip}{2pt} % space above captions
\setlength{\belowcaptionskip}{0pt} % space below captions
\setlength{\textfloatsep}{2pt}     % space between last top float or first bottom float and the text
\setlength{\floatsep}{2pt}         % space left between floats
\setlength{\intextsep}{2pt}        % space left on top and bottom of an in-text float

% print LaTeX dimensions
\usepackage{printlen}

% reduces footer text separation adjusted for page numbers
\setlength{\footskip}{14pt}

% scales down page number font size if document is at 12pt -> page numbers 10 pt
\renewcommand*{\thepage}{\footnotesize\arabic{page}}

\begin{document}

The \verb|\textwidth| is \printlength{\textwidth} which is also
\uselengthunit{in}\printlength{\textwidth} and
\uselengthunit{mm}\printlength{\textwidth}.

\uselengthunit{pt}
The \verb|\textheight| is \printlength{\textheight} which is also
\uselengthunit{in}\printlength{\textheight} and
\uselengthunit{mm}\printlength{\textheight}.

\end{document}

Open Source Hilbert for the Kindle

David Hilbert

David Hilbert

While searching for free Kindle books I found Project Gutenberg. Project Gutenberg offers free Kindle books but they also have something better! Would you believe \LaTeX source code for some mathematical classics.

The best book I’ve found so far is an English translation of David Hilbert’s Foundations of Geometry. Hilbert’s Foundations exposed some flaws in the ancient treatment of Euclidean geometry and recast the subject with modern axioms. Because it is relatively easy to follow, compared to Hilbert’s more recondite publications, this little book exercised disproportionate influence on 20th century mathematics. We still see its style aped, but rarely matched, in mathematics texts today.

I couldn’t resist the temptation of compiling a mathematical classic so I eagerly downloaded the source and ran it through \LaTeX.  Foundations compiled without problems and generated a nice letter-sized PDF. Letter-size is fine but I was looking for free Kindle books! I decided to invest a little energy modifying the source to produce a Kindle version. Project Gutenberg makes it clear that we are free to modify the source. Isn’t open source wonderful!

Converting Foundations was simple. The main \LaTeX file included 52 *.png illustrations with hard-coded widths in \includegraphics commands. I wrote a J script that converted all these fixed widths to relative \textwidth‘s. This lets \LaTeX automatically resize images for arbitrary page geometries. When compiled with Kindle page dimensions this fixed most of the illustrations. I had to tweak a few wragfig‘s to better typeset images surrounded by text. The result is a very readable Kindle oriented PDF version of Hilbert’s book. There are still a few problems. The Table of Contents is a plain tabular that does not wrap well and one table rolls off the right Kindle margin. Neither of these deficiencies seriously impair the readability of the text.  If these defects annoy you download the Project Gutenberg source with my modifications and build your own version.

This little experiment convinced me that providing free classic books, in source code form, is a service to mankind.  Not only does it allow you to “publish” classics on new media it also fundamentally changes your attitude toward books. Hilbert was one of the great mathematical geniuses of the 19th and 20th century. It’s hard to suppress we are not worthy moments and maintain a sharp critical eye when reading his “printed” works.  You don’t get the same vibe when reading raw \LaTeX.  Source code puts you in a, it’s just another bug infested program, frame of mind. You expect errors in code and you typically find them. This is exactly the hard-nosed attitude you need when reading mathematics.