[forgetfulness]

That author uses it to mean “model”, as he calls a variety of programming models “spherical cows”.

Well, for sure, a core tenet of computer science is that all models of computing are equally powerful in what inputs they can map to what outputs, if you set aside any other details

[wk_end]

He uses it to mean all sorts of things. He describes "string interpolation" as a "spherical cow".