[comp.lang.postscript] Why a postscript language?

josh@dewey.soe.berkeley.edu (Josh Putnam) (01/03/90)

Why is PostScript the way it is? Why not use a lisp-like language?
Is it because of the simple implementation? Does a postscript language
make page description easier?

Josh Putnam

woody@rpp386.cactus.org (Woodrow Baker) (01/03/90)

In article <33444@ucbvax.BERKELEY.EDU>, josh@dewey.soe.berkeley.edu (Josh Putnam) writes:
> 
> Why is PostScript the way it is? Why not use a lisp-like language?
> Is it because of the simple implementation? Does a postscript language
> make page description easier?
> 
> Josh Putnam
A threaded style language, with a RPN structure is inherantly easier and
faster to interpret.  As for making page descriptions easier, it does not.
Describing the page is a separate operation.  What Postscript does is give
you an incredably powerful programming language, and an imaging model
that allows the RENDERING of the page to be size independant as well as
sophisticated.  Because you are essentially creating a program to image
out a page, much of the work can be pushed off on the printer.  The
ability to scale and rotate images and text enables the RENDERING of
the page to be more general and flexible than that of say a bit-mapped
page. or even a fixed font size implementation.

Cheers
Woody
 

amanda@mermaid.intercon.com (Amanda Walker) (01/04/90)

In article <33444@ucbvax.BERKELEY.EDU>, josh@dewey.soe.berkeley.edu (Josh
Putnam) writes:
> Why is PostScript the way it is? Why not use a lisp-like language?
> Is it because of the simple implementation? Does a postscript language
> make page description easier?

One thing that PostScript has over Lisp is that it's very easy to do a
Forth-style threaded implementation.  Lisp storage allocation in particular
can be much more complex, and with only so much RAM to play with, a
stack-based threaded language can give you more "bang for the buck".
It's also marginally easier to generate from a program (unless that program
is written in Lisp :-)), which is nice for things like output drivers,
emulators, and so on.

Does anyone know what ever happened to LispScript?  It was a baby Lisp
interpreter that compiled into normal PostScript.

Amanda Walker
InterCon Systems Corporation
--