Thank you, Mr. Kawai.  I have pushed this to the SRFI 134
repository.

Here is the diff:

  <https://github.com/scheme-requests-for-implementation/srfi-134/commit/6e3e0f6cba1f710e5e1848c25b95b346ded92010>

John, when you have a chance, would you please update the
Implementation section to describe both implementations?
Here's what it says now:

  The sample implementation is (not yet) in the repository
  for this SRFI.  It is an implementation based on two
  Scheme lists, one for the front and another (in reverse
  element order) for the back.  The cost of ideque-front,
  ideque-back, ideque-remove-front, and ideque-remove-back
  are amortized O(1).  An implementation based on finger
  trees will be added later.

You were probably already planning to do this, but I thought
I'd mention it, just in case.

It might also be nice to have a "README.txt" file in each of
the implemementation's subdirectories.

Thanks.

Shiro Kawai <xxxxxx@github.com> writes:

| Based on Chris Okasaki's book.
| Depends on srfi-1, srfi-9 and srfi-121.
| Tested on Gauche R7RS mode.
>
| Commit Summary
>
| * Reference implementation of ideque using 2-list approach
>
| File Changes
>
| * A ideque-2list/ideque-impl.scm (457)
| * A ideque-2list/ideque-tests.scm (203)
| * A ideque-2list/ideque.sld (32)
| * A ideque-2list/run-tests.scm (14)