A primer and a main charge. Very dense. Goes from nothing to walking
binary trees and macros in about a hundred nicely sequenced
steps. Wish I'd had this when we did SICP. Bookmarked to give to
students.
It isn't. That was the GP either misunderstanding or, perhaps more probably, making a pun. The usage here is this sense of the word: https://en.wikipedia.org/wiki/Primer_%28textbook%29
(Then again, maybe your comment was just a way of saying "ISWYDT!" to the GP?)