On 2020-07-19 20:55 -0400, Wolfgang Corcoran-Mathe wrote:
>
>     (indexer lower-bound n) = (indexer (indexer lower-bound n) 0)
>
> If a range's indexer satisfies this law, we can freely create
> subranges by moving the lower bound about.  It seems to be a
> fundamental property of sequences ...

By "a fundamental property of sequences", I mean "of indexer functions
which generate a sequence".  The fundamental property of *sequences*
is that a choice of lower bound doesn't change the elements in the
underlying collection.

--
Wolfgang Corcoran-Mathe  <xxxxxx@sigwinch.xyz>