Szymon Kaliski

Lambda Encoding

• attempt at articulation of an idea prompted by some discussions at Ink&Switch (though much older now, dating back to PostScript) - what if documents were described not as a "structure", but as a program that generates that structure
• if I squint, this looks similar to "Kolmogorov Complexity"

  Kolmogorov complexity of an object, such as a piece of text, is the length of a shortest computer program (...) that produces the object as output

Several of the best graphics people at PARC created an excellent "printing standard" for how a document was to be sent to the printer. This data structure was parsed at the printer side and followed to set up printing.

But just a few weeks after this, more document requirements surfaced and with them additional printing requirements.

This led to a "sad realization" that sending a data structure to a server is a terrible idea if the degrees of freedom needed on the sending side are large.

And eventually, this led to a "happy realization", that sending a program to a server is a very good idea if the degrees of freedom needed on the sending side are large.

(...)

Key Point: "sending a program, not a data structure" is a very big idea (and also scales really well if some thought is put into just how the program is set up).

— Should web browsers have stuck to being document viewers? ↗ - Alan Kay

• big thing to solve here is sandboxing - safely executing random code sent to you is a much harder thing than parsing a well-defined schema; this is an issue with PostScript too - maybe it's not a "big deal" since it's a printer?

  Infinite loops One trivial example of an infinite loop written in PostScript is given below:

  %!
  {} loop
  

  This minimalist document keeps a PostScript interpreter busy forever. In an evaluation with a pool of 20 test printers, only one had a watchdog mechanism and restarted itself after about 10 minutes. The other devices did not accept print jobs anymore until the test was ultimately interrupted after half an hour.

  — http://hacking-printers.net/wiki/index.php/Document_processing ↗

• on the other hand, aren't JavaScript single-page-apps already this in "reverse" - the clients receive code to execute, not a rendered document