[r6rs-discuss] [Formal] Requirement to detect circular lists

From: William D Clinger <will>
Date: Tue Oct 3 10:19:27 2006

I am posting this as an individual member of the Scheme
community. I am not speaking for the R6RS editors, and
this message should not be confused with the editors'
eventual formal response.

Andre van Tonder wrote:
> By the way, the draft never seems to define "plausible list" when initial
> and final times are not specified, yet uses it everywhere without specifying
> these times. Am I missing something?

Not much. Section 23.2, fourth paragraph:

    Plausible lists are defined with respect to the
    time interval between the time an argument is
    passed to the specified procedure and the first
    return of a value to that procedure's continuation.

What that paragraph doesn't say, but should, is that
the t_0 normally corresponds to procedure entry, and
t_n to some time *before* the first return. For more
precise specifications, see section 23.3.2. Perhaps
section 23.3.1 should be as precise as 23.3.2 (which
is itself not fully precise).

Will
Received on Tue Oct 03 2006 - 10:19:23 UTC