While researching formal methods, I found NASA’s PVS libraries which are half written in Common Lisp. I was intrigued by the third in PostScript, a language I’d never heard of…

For sure, I thought, that must be a tool of arcane, darkling power (and not just used to display PDFs.) Indeed, it is an exotic concatenative language with lispy data structures, a GC and strong dynamic typing (though only for built ins.)

Materials

Reference manual red book has 500 pages of code examples and explanations before the actual reference material!

tutorial and cookbook or blue book)

Postscript language program design green book