I've just published draft #4 of SRFI 143.  It was submitted
by John Cowan, author of the SRFI.

<https://srfi.schemers.org/srfi-143/>

Here's the diff:

<https://github.com/scheme-requests-for-implementation/srfi-143/commit/5d91d81a4ba616c2359a2e06d83ebbab75885e4c>

Here is John's earlier message with comments on this draft:

<http://srfi-email.schemers.org/srfi-143/msg/5506169>

Sorry for the delay.

Regards,

SRFI Editor