I've just published draft #4 of SRFI 234. It was submitted by Arne Babenhauserheide, co-author of the SRFI.

Here are Arne's comments on the draft:

Remove exception-throwing version and add optional vector of nodes for large graphs or non-comparable nodes

Here is the commit summary:

Here's the diff:

https://github.com/scheme-requests-for-implementation/srfi-234/compare/draft-3..draft-4

Regards,

SRFI Editor