If these books have APL adjustable rank ⍤ used on the `for` function, we can make many more combinations:

    "J for⍤0 0⊢ C Programmers" ≢ J for C programmers.

    "J for⍤1 0⊢ C Programmers" ≢ J++ for C programmers.

    "J for⍤0 1⊢ C Programmers" ≢ J for C++ programmers.

    "J for⍤1 2⊢ C Programmers" ≢ J++ for C# programmers.

    "J for⍤2 2⊢ C Programmers" ≢ J# for C# programmers.

etc. Then with `commute` ⍨ we can swap the argument order as well:

    "J for⍨⍤1 0⊢ C Programmers" ≢ C++ for J programmers.

etc.

(Assuming C has a single implicit plus, C++ is a 1D array of plusses, C# has a 2D matrix of plusses)

J++ was actually a real thing. I wouldn’t be surprised if that book had been written.