I've just published draft #4 of SRFI 189. It was submitted by John Cowan, co-author of the SRFI.

Here are John's comments on the draft:

I think this is ready for last call now. Wolfgang's implementation will catch up shortly.

Note that I am waiting to announce last call until the implementation and tests are complete.

Here is the commit summary:

• fold functions accept all values plus nil
• Implement Draft #3 of SRFI 189 (multiple values).
• Remove maybe-contains? and either-contains?.
• clarified -sequence operations
• maybe->list mutation is an error
• Update -sequence functions.
• Remove tests for -contains procedures.
• Update test sets: predicates, accessors, join and bind.
• Delete "obj" argument in either-remove and -filter.
• Update test sets: sequence operations, conversions.
• Fix arity error in either->lisp-values.
• Update test set for map, fold, unfold.
• Return unspecified value from -for-each procedures.
• Fix typos in definition of maybe-if.
• Improve the bargain basement SRFI 78 implementation.
• Comment cleanup and improvement.
• Add tests for `maybe-if'.
• Refactor some tests for readability.
• style typos
• Lefts now contain exactly one value
• Show keywords.
• Use HTML links on HTML pages.
• Fix typo. Publish fourth draft.

Here's the diff:

https://github.com/scheme-requests-for-implementation/srfi-189/compare/draft-3..draft-4

Regards,

SRFI Editor