Thank you for taking a look Maxime. I have accidentally replied to just
you and not the whole list, so there might be a duplicate email.

> How about including the tests
> (https://github.com/scheme-requests-for-implementation/srfi-214/blob/master/implementation/tests.scm)
> as well?
>
> Guile doesn't use SRFI-64 in its own tests though, so some changes may
> be necessary.

I've converted and added the tests to the patch. It passes with no
issues on my end.

> however, the README says ‘by Adam Nelson’.  Did you reach some kind of
> agreement with Adam Nelson about copyright assignment?  And since SRFIs
> are licensed under Expat (not 100% sure), wouldn't this need to be the
> Expat license text?
>
> Even if the Expat license allows this (I don't know), then I would
> still recommend to keep the license the same, such that fixes can
> easily be interchanged between Scheme implementations (e.g. there have
> been some fixes to SRFI-64 a while ago).

There was no copyright assignment. The expat license is GPL compatible,
so I assumed GPL would be the preferred license for a contribution to
Guile. I can definitely change the license for my edits to whatever is
best for Guile. The license for srfi-214's sample implementation is
definitely expat, given the SRFI process errata
<https://srfi.schemers.org/srfi-process.html> and the working repository
of the implementation
<https://github.com/ar-nelson/scheme-flexvectors/blob/master/LICENSE>

I have attached the updated patch.

~ Vijay