Code from The Reasoned Schemer, Second Edition, by Daniel P. Friedman, William E. Byrd, Oleg Kiselyov and Jason Hemann, 2018 MIT Press.
https://mitpress.mit.edu/books/reasoned-schemer-second-edition
trs2-impl.scm includes the implementation of the language used in the book, from Chapter 10 & Appendix A
trs2-arith.scm includes the arithmetic relations from Chapters 7 & 8 (please load trs2-impl.scm before loading trs2-arith.scm)
Example of loading and testing the code in Scheme, assuming you start Scheme in the same directory as the code
> (load "trs2-impl.scm")
> (run* q (== 'pasta q))
(pasta)
> (load "trs2-arith.scm")
> (run* q (*o (build-num 3) (build-num 4) q))
((0 0 1 1))
>
You can find more about the language of the book at http://minikanren.org/