The History of the Schwartzian Transform
Sep 2, 2016 by brian d foy
The history of the Schwartzian Transform is fascinating, full of intrigue, competing philosophies, and cross-language reluctant cooperation. The Schwartzian Transform is the name applied to a particular implementation of a cached-key sorting algorithm.
The first public appearance is probably Randal Schwartz’s Usenet post on December 16, 1994 in response to Ken Brown’s request for help:
Randal didn’t name it. He wrote the code and essentially dropped the mic. He says that he was on a break from teaching a Perl class, so his response was brief and unexplicated - typical for an experienced Usenet denizen (he said that he was there when you could read all of Usenet in a half hour). I don’t think he expected it to be as troublesome as it turned out to be.
His code isn’t that complex. It’s a big statement, but when I teach it in Perl classes, I tell people to read it from the end toward the beginning (a handy technique for any list pipeline):
