Saturday, February 23, 2008

PostScript is turing complete

Yes, PostScript is turing complete so next time you get a different output when printing with kpdf than the one you get when doing print preview in kpdf, specially if the print preview looks correct, blame whoever decided to use such a complex language for printers and also the drivers of your printer for not being able to understand it, do not blame kpdf.


Anonymous said...

Yes, it is. That's why it's called a page description *language*. It was heavy influenced by Forth wich was at that time (and still is?) a
proper way to program an embedded system like the RIP of a laser printer.

Maybe it is too complex, but it prevented us for for now some 30 years using some Microsoft "standard" for printing, as MS often tried to take control over the printer market (GDI, Metro Printpath, ...) and is still trying.

So be a little bit more respectful to the "Old Lady" Postscript, even if it's design seems to be inappropriate from todays view. Being Turing complete is not a bad thing in the first place. Postscript undeniable did it's work: It's still here, despite all attacks from Microsot to squeeze it out of the market as *the* file format and language for professional grade printing.

And without Postscript we wouldn't have PDF.

It's not that I'm a big Adobe fan, but Postscript surely wasn't the worst they have done.

(I'm sure you already noticed, I'm the guy who asked why kpdf --- thank for that, really good work! --- should display Postcript at all on the dot some years ago)

Anonymous said...

Ah, this explains why these postscripts will not render in kpdf .. :-)

Albert Astals Cid said...

@thomas, Sorry to bust your bubble, but kpdf has never rendered postscript. You are able to open then but all we do is run ps2pdf on them and render the pdf, so if these postscripts don't work is not kpdf fault