Yes, it looks like (besides the leftover "ITA" comment in the guide!) that this is simply the ITA guidelines. From Carl's remarks, you can tell that ITA is not a 'normal' Lisp program. Most Lisp programs do not preallocate ~5K of data structures and fail-fast if they exceed that, for example.
ITA actually has two large Lisp systems. One of them is the insanely optimized fare search system (QPX) that does all the crazy things described in the link. The other is the airline reservation system which is a much more conventionally coded Lisp system.
Comments
Yes, it looks like (besides the leftover "ITA" comment in the guide!) that this is simply the ITA guidelines. From Carl's remarks, you can tell that ITA is not a 'normal' Lisp program. Most Lisp programs do not preallocate ~5K of data structures and fail-fast if they exceed that, for example.
Compare to the more conventional Norvig style guide (who is also of course at Google today, coincidentally): http://www.cs.umd.edu/~nau/cmsc421/norvig-lisp-style.pdf (PDF)
ITA actually has two large Lisp systems. One of them is the insanely optimized fare search system (QPX) that does all the crazy things described in the link. The other is the airline reservation system which is a much more conventionally coded Lisp system.