texmath

texmath is a Haskell library for converting between formats used to represent mathematics. Currently it provides functions to read and write TeX math, presentation MathML, and OMML (Office Math Markup Language, used in Microsoft Office), and to write Gnu eqn, typst, and pandoc’s native format (allowing conversion, using pandoc, to a variety of different markup formats). The TeX reader and writer supports basic LaTeX and AMS extensions, and it can parse and apply LaTeX macros. The package also includes several utility modules which may be useful for anyone looking to manipulate either TeX math or MathML. For example, a copy of the MathML operator dictionary is included.

You can try it out online here.

By default, only the Haskell library is installed. To install a test program, texmath, use the executable Cabal flag:

cabal install -fexecutable

By default, the executable will be installed in ~/.cabal/bin.

Alternatively, texmath can be installed using stack. Install the stack binary somewhere in your path. Then, in the texmath repository,

stack setup
stack install --flag texmath:executable

The texmath binary will be put in ~/.local/bin.

Macro definitions may be included before a LaTeX formula.

Running texmath as a server

texmath will behave as a CGI script when called under the name texmath-cgi (e.g. through a symbolic link). The file cgi/texmath.html contains an example of how it can be used.

But it is also possible to compile a full webserver with a JSON API. To do this, set the server cabal flag, e.g.

stack install --flag texmath:server

To run the server on port 3000:

texmath-server -p 3000

Sample of use, with httpie:

% http --verbose localhost:3000/convert text='2^2' from=tex to=mathml display:=false Accept:'text/plain'
POST /convert HTTP/1.1
Accept: text/plain
Accept-Encoding: gzip, deflate
Connection: keep-alive
Content-Length: 64
Content-Type: application/json
Host: localhost:3000
User-Agent: HTTPie/3.1.0

{
    "display": false,
    "from": "tex",
    "text": "2^2",
    "to": "mathml"
}


HTTP/1.1 200 OK
Content-Type: text/plain;charset=utf-8
Date: Mon, 21 Mar 2022 18:29:26 GMT
Server: Warp/3.3.17
Transfer-Encoding: chunked

<math display="inline" xmlns="http://www.w3.org/1998/Math/MathML">
  <msup>
    <mn>2</mn>
    <mn>2</mn>
  </msup>
</math>

Possible values for from are tex, mathml, and omml. Possible values for to are tex, mathml, omml, eqn, and pandoc (JSON-encoded Pandoc).

Alternatively, you can use the convert-batch endpoint to pass in a JSON-encoded list of conversions and get back a JSON-encoded list of results.

Generating lookup tables

There are three main lookup tables which are built form externally compiled lists. This section contains information about how to modify and regenerate these tables.

In the lib direction there are two sub-directories which contain the necessary files.

MMLDict.hs

The utility program xsltproc is required. You can find these files in lib/mmldict/

1. If desired replace unicode.xml with and updated version (you can download a copy from here
2. xsltproc -o dictionary.xml operatorDictionary.xsl unicode.xml
3. runghc generateMMLDict.hs
4. Replace the operator table at the bottom of src/Text/TeXMath/Readers/MathML/MMLDict.hs with the contents of mmldict.hs

ToTeXMath.hs

You can find these files in lib/totexmath/

1. If desired, replace unimathsymbols.txt with an updated version from here
2. runghc unicodetotex.hs
3. Replace the record table at the bottom of src/Text/TeXMath/Unicode/ToTeXMath.hs with the contents of UnicodeToLaTeX.hs

ToUnicode.hs

You can find these files in lib/tounicode/.

1. If desired, replace UnicodeData.txt with an updated verson from here.
2. runghc mkUnicodeTable.hs
3. Replace the table at the bottom of src/Text/TeXMath/Unicode/ToUnicode.hs with the output.

Editing the tables

It is not necessary to edit the source files to add records to the tables. To add to or modify a table it is easier to add modify either unicodetotex.hs or generateMMLDict.hs. This is easily achieved by adding an item to the corresponding updates lists. After making the changes, follow the above steps to regenerate the table.

The test suite

To run the test suite, do cabal test or stack test.

In its standard mode, the test suite will run golden tests of the individual readers and writers. Reader tests can be found in test/reader/{mml,omml,tex}, and writer tests in test/writer/{eqn,mml,omml,tex}. Regression tests linked to specific issues are in test/regression.

Each test file consists of an input and an expected output. The input begins after a line <<< FORMAT and the output begins after a line >>> FORMAT.

If many tests fail as a result of changes, but the test failures are all because of improvements in the output, you can pass --accept to the test suite (e.g., with --test-arguments=--accept on stack test), and the existing golden files will be overwritten. If you do this, inspect the outputs very carefully to make sure they are correct.

If you pass the --roundtrip option into the test suite (e.g., using --test-arguments=--roundtrip with stack test), round-trip tests will be run instead. Many of these will fail. In these tests, the native inputs in test/roundtrip/*.native will be converted to (respectively) mml, omml, or tex, then converted back, and the result will be compared with the starting point. Although we don’t guarantee that this kind of round-trip transformation will be the identity, looking at cases where it fails can be a guide to improvements.

Authors

John MacFarlane wrote the original TeX reader, MathML writer, Eq writer, and OMML writer. Matthew Pickering contributed the MathML reader, the TeX writer, and many of the auxiliary modules. Jesse Rosenthal contributed the OMML reader. Thanks also to John Lenz for many contributions.