Another thing about that code that I think irks some folks but is also reminds me of reading math is that it's much easier if you are aware of some common conve

Another thing about that code that I think irks some folks but is also reminds me of reading math is that it's much easier if you are aware of some common conventions and notation. For instance, the lines: #define V1(f) A f(w)A w; #define V2(f) A f(a,w)A a,w; Are much more quickly recognizable if you know that in APL the left and right arguments to a function are alpha (α) and omega (ω), so you'd immediately recognize these macros as for defining 1-argument and 2-argument functions. For folks in the know, conventions like this allow quicker communication and expression, but they also raise the barrier somewhat to the uninitiated. Side note for folks used to "modern" (post 1989) C code - this is old K&R style function definition. This SO post (https://stackoverflow.com/a/3092074 https://stackoverflow.com/a/3092074) shows a comparison.