SWI isn't not supported exactly. Starting particularly with version 7 SWI has introduced some non iso conforming extensions/changes. '[|]' instead of '.' for th

SWI isn't not supported exactly. Starting particularly with version 7 SWI has introduced some non iso conforming extensions/changes. '[|]' instead of '.' for the list functor and a dedicated string type among other things and Jan (the main author of SWI) has been clear that he's willing to change other stuff. Triska has both some technical as well as aesthetic/philosophical issues with these changes but also from a practical stand point it means that while SWI is pretty much entirely compatible with the book today it might not be tomorrow. Ciao is another implementation that is mature and pretty compliant but also openly willing to break compliance. That all said it's a bit of a shame because Scryer has basically no documentation and GNU looked abandoned until pretty recently.