That is indeed a good post; thanks for linking it. Beyond the sort itself, there's a nice illustration at the end of dynamically scoped ("special") variables be

That is indeed a good post; thanks for linking it. Beyond the sort itself, there's a nice illustration at the end of dynamically scoped ("special") variables being useful on occasion for something other than the usual example of temporarily shadowing a configuration variable (e.g. the destination of stdout, or logging level).