Dear gang,

With a couple of modifications I got tikz-cd (a package to make  
commutative diagrams for categories and toposes etc. by Florêncio Neves)  
working in mkiv:

http://texdoc.net/texmf-dist/doc/latex/tikz-cd/tikz-cd-doc.pdf

It depends on the tikz module, already supported in mkiv.

The tikz-cd module is attached, and here is a sample file:

===============
\usemodule[tikz]
\usetikzlibrary{commute}

\starttext
\starttikzcd %[ampersand replacement=\&]
A \arrow{rd} \arrow[yshift=0.5ex]{r}{\phi} \& B \\
\& C
\stoptikzcd

\starttikzcd %[ampersand replacement=\&]
A
\arrow[yshift=1.5ex]{r}
\arrow[yshift=0.0ex]{r}
\& B \arrow[xshift=0.7ex]{d} \arrow[xshift=-0.7ex]{d} \\
\& C
\stoptikzcd
\stoptext
===============

A couple of things:

1 I had to comment out line 396 of pgfsys-pdftex.def in the tikz module,  
or else I'd get an undefined control sequence. It's not needed anyway  
since that's pdftex.

2 In tikzlibrarycommute.code.tex, line 395 I had to add the option

ampersand replacement=\&

to avoid a TeX error. So you'll have to use '\&' instead of '&' for matrix  
arrays.

3 Some LaTeX-specific stuff is commented, and support is added for

\starttikzcd \stoptikzcd

so we get a ConTeXt environment.


I'm hoping someone can volunteer to place this on the wiki, perhaps even  
set it up on the modules page, with an indication of its proper place in  
the texmf-modules tree etc.

Any other improvements will also be appreciated. Enjoy!

Best wishes
Idris
-- 
Professor Idris Samawi Hamid
Department of Philosophy
Colorado State University
Fort Collins, CO 80523