update 1: latex http://www.latex-project.org and http://tex.stackexchange.com/questions/12668/where-do-i-star...
update 0: so open tools for postscript appear to be really interfacing AGPL ghostscript (postscript) api if you can handle the ^agpl^ restrictions ~ https://en.wikipedia.org/wiki/Ghostscript
- https://en.wikipedia.org/wiki/PostScript
- language reference Adobe V3 https://www.adobe.com/products/postscript/pdfs/PLRM.pdf
- postscript as programming language http://www.ugrad.math.ubc.ca/Flat/lang.html
- First guide to Postscript http://tailrecursive.org/postscript/postscript.html
- L-systems in Postscript http://www.cs.unh.edu/~charpov/programming-lsystems.html
- The PostScript programming language http://www.cburch.com/csbsju/cs/portfolio/postscript.pdf
- Postscript Tutorial and Cookbook https://www-cdf.fnal.gov/offline/PostScript/BLUEBOOK.PDF
- PDF vs Postscript https://www.reddit.com/r/programming/comments/kssyt/postscri...
- Learn Postscript by Doing https://staff.science.uva.nl/a.j.p.heck/Courses/Mastercourse...
- Open Source PDF Libraries and Tools http://pdf-house.blogspot.com.au
- gnu plot http://gnuplot.sourceforge.net/demo/index.html (https://opensourceforu.com/2011/01/plotting-is-fun-with-gnup...)
- Postscript software https://en.wikipedia.org/wiki/List_of_PDF_software
- Ghostscript https://www.ghostscript.com/index.html
- Adobe OS tools https://github.com/adobe/adobe.github.com
- xpost interpreter for the PostScript Language https://groups.google.com/forum/#!forum/xpost-discuss / https://github.com/luser-dr00g/xpost
I don't have a copy of the coding practices written down any more, but here are some examples:
I wrote pizzatool at Sun, as a programming example to show how to use the NeWS toolkit, so it was well commented and intended to be read by developers learning NeWS:
http://www.donhopkins.com/home/code/pizzatool.ps.txt
http://www.art.net/~hopkins/Don/images/pizzatool.gif
Here's a typical NeWS user interface widget that I wrote at Sun following the NeWS coding practices, including the OPEN LOOK slider and menu:
http://www.donhopkins.com/home/code/slider.ps.txt
http://www.donhopkins.com/home/code/menu.ps.txt
http://www.art.net/~hopkins/Don/images/tnt.gif
This is older code I wrote on my own before working at Sun, so it's not as rigorously formatted or well documented:
http://www.donhopkins.com/home/code/piemenu.ps.txt
http://www.donhopkins.com/home/code/term.ps.txt
And here's a huge file of messy PostScript code I wrote, with a warning at the beginning about how ugly it is:
http://www.donhopkins.com/home/code/litecyber.ps.txt
And here's some really old NeWS code written by James Gosling: