scryer-shen

> "cardinal sin of breaking portability. Basically every Prolog ever does that. Every single one." Indeed; still Markus Triska speaks positively about, and recommends, different Prolog systems. He seems to prioritise things above ISO purity, and is not king of the hill of Scryer Prolog[1], he doesn't comment like others who act as if "the village and city can burn to the ground for all I care, heresy against ISO Prolog is NEVER acceptable". So when he's finding this objectionable even after considering that, it seems reasonable for me to weight it more strongly. It's not enough to make me stop using SWI, or stop me recommending it (as I did above). [1] for other readers, Mark Thom's Prolog-in-Rust to be a type inference engine for his Lisp-in-Rust: https://github.com/mthom/scryer-shen

I've spinning up a new Shen implementation from scratch, in Racket, which integrates directly with my Prolog implementation, Scryer Prolog: https://github.com/mthom/scryer-shen/ Several innovations are documented in the README. Both the Prolog implementation and the type checker are written in / hosted by Scryer (Prolog implementation is done, the type checker is in progress). Scryer has many powerful constructs for monotonic reasoning which should help to take Shen's type checker in particular to new heights of power!