$ whois postscript

PostScript

first released in 1982 · by John Warnock, Chuck Geschke

$ guessprog --inspect postscript

year: 1982
paradigm: concatenative
family: forth
memory: automatic gc
binding: dynamic
safety: weak

POSTSCRIPT(7)

AUTHORS: John Warnock, Chuck Geschke
HISTORY: John Warnock and Chuck Geschke left Xerox PARC, where they had worked on the Interpress page description language, and founded Adobe in 1982 to build PostScript. Instead of sending pixels, a computer sends the printer a program that draws the page, using a stack-based language in the tradition of Forth. Its first big success was the Apple LaserWriter in 1985, which together with the Macintosh and PageMaker started the desktop publishing revolution.
USAGE: Largely superseded by PDF, which was derived from it, PostScript is still understood by many printers and produced by tools such as dvips. Ghostscript keeps an open source interpreter alive, and a few enthusiasts still write it by hand.
SEE ALSO: PostScript on Wikipedia ↗

$ cat hello.ps

%!PS
/Helvetica findfont 24 scalefont setfont
72 720 moveto
(Hello, printer!) show

% a procedure: n fact -> n!
/fact {
  dup 1 le { pop 1 } { dup 1 sub fact mul } ifelse
} def

72 680 moveto
5 fact 20 string cvs show   % draws 120
showpage