Old School APL vs. D-fns

Looking at the D-fns code I am writing to build my Co-Dfns compiler. I have to wonder what kind of horror might the old school APLers experience if they examined my source code. Would they freak out at the use of proofs, assertions, and other structural content designed to formally convince the reader that my code is correct? Or would they just freak out at the curly braces?