It isn't a mathematical formalism. I have studied books on lambda calculus and all that. A computer scientist's understanding of what "well-defined" means is ve

It isn't a mathematical formalism. I have studied books on lambda calculus and all that. A computer scientist's understanding of what "well-defined" means is very different from a mathematician's. It's not to say that it doesn't work, just that the standard is very very different. The standard of well-definedness for a physicist and a mathematician is also very different. Example: compare what constitutes a "good enough" definition of a real number to these three disciplines.