xxxxxx@freenetproject.org wrote:
> Actually, I'm vehemently against collection-fold ever looping over a
> circular but finite collection.  Half of the advantage of collection
> fold is that it allows you to pass functions unaware of the properties
> of the underlying collection and let the implementation handle
> retrieving all the requisite values.
>
> Potentially or actually infinite collections are another matter ....

So it depends on the "true nature" of the collection, then. Examples:

A modulo-sequence lets you use wrap-around indexes (like -1 or bignum)
but it's really a finite sequence, so *-size returns a true value, and
collection-fold halts.

An infinite-sequence really is infinite, even if its internal
representation isn't, so *-size returns #f, and collection-fold does not
halt.

Based on this, I say: Tighten up the definitions of *-size and fold to
make this more obvious, but otherwise no changes. There's no need for
finite-collection?, because it's essentially equivalent to *-size under
this interpretation.
--
Bradd W. Szonye
http://www.szonye.com/bradd