This is worth a look. Some of the old A+ stuff is as well. I'm told by reliable sources that an awful lot of Art's code looked like this over the years; even the more recent K7 stuff. Art's gonna do his thing. Opinions differ as to whether or not it is a generally good idea, but you can't argue with the results, and at this point I find stuff like the J source code to be fairly readable, even if it is really different from what most people are used to. Basically, you're just expressing C as APL primitives. If you understand APL primitives, it's not so bad.
If you want to see APL expressed as C primitives, something like Nial is pretty good: https://github.com/danlm/QNial7