A Critical Review of "Type Checking with Rewriting Rules" from ACM SLE 2024

This review paper, based on Chapter 4 of "A: to Z: of ACM SLE Since 2008 --- towards discovery of a modern programming language" also by the author, presents a critical review of the ACM SLE 2024 publication titled "Type Checking with Rewriting Rules" by Assistant Professor Dimi Racordon (Laboratoire de Méthodes de Programmation, or Programming Methods Laboratory --- École Polytechnique Fédérale de Lausanne, Switzerland). We summarize our appreciation of that paper, highlight its key ideas, and provide critical and comparative analysis commentary based on handwritten review notes compiled between 2024 and 2026. Special attention is given to parallels between Racordon's work on Swift and Hylo using the generics meta-programming calculus FG applied to type classes and our own Transforming Executable Alphabet (TEA) project. The review concludes with lessons learned and implications for future research in software language engineering. Overall, we established that functional languages (but also OOPLs) that might actually better be suited for complex type systems such as those leveraging type classes, do not necessarily overhaul unitype system languages that are provably simpler to design, implement and maintain --- especially given that, as per Lutalo's UPLT (Unifying Programming Language Theory, 2024), any such languages, but also their algorithms on Turing Machines, can be reduced to implementations oriented towards pure text processing such as with TEA. Moreover, we have established that it is possible, and we have demonstrated with FG and TEA Data Templates, how one might realize type class functionality in a unitype language. In conclusion, we establish that Racordon's paper made a tremendous contribution towards promoting use of the language-agnostic FG for expressing problems and solutions about generic programming.