PostScript is a reverse-polish stack-based, dynamically-typed, dynamic-namespacing, scripting language with built-in primitives for generating rendered images from vector descriptions. PostScript employs the same “Adobe Image Model” as the PDF file format.
PostScript is used as an output format by many programs since it is designed to be easily machine-generated.
Like LISP, PostScript is homoiconic and code and data share the same representation. Procedures can take procedures as data and yield procedures as results, lending itself to techniques from concatenative-programming as well.