[m-dev.] for review: switches via binary search

[Zoltan Somogyi]

Fergus wrote:
> It might be more elegant to implement this using list__filter/4.

OK, I will.

> Ditto.  Hang on, how does this differ from the previous one?

You are right, the code is identical, but the types are different. I could
substitute a polymorphic predicate, but using list__filter is better.

> Hmm, didn't I see that already?

Possible. I had to stitch the diff together from two base diffs, because
a "cvs diff" in the root directory consistently gave me a disk block full
of NUL characters. (munkora was running a defragment program at the time,
and either it or NFS has a bug.) It seems I did not remove all duplication
as I had intended. (The fact that vim got internal errors while deleting
the block of NULs didn't help.)

I will also make the changes suggested in your other mail. (The change
from < to =< in the size option comparisons was a minor bug fix; it will be
documented in the log message as such.)

Zoltan.