On Wed, Jul 12, 2017 at 3:08 AM, Marc Nieper-Wißkirchen <xxxxxx@nieper-wisskirchen.de> wrote:

As implementers are only "encouraged" to provide an implementation solely based on hash tables, portable code will need some means to detect statically whether the implementation provides hash sets and bags.

The intention is that Orange Edition (not Yellow, as I wrote above) implementers must accept hash-only comparators. Even if people who implement SRFI 146 with the Red Edition or plain R7RS or earlier standards don't feel compelled to, they should. :-)