On Tue, 23 Nov 2010 16:05 -0500, "John Cowan" <[email protected]>
wrote:
> Christopher Chittleborough scripsit:
> 
> > (chronology-with-time-zone CHRONOLOGY TIMEZONE)
> >   Presumably a "time zone name" is a string. Say so explicitly?
> 
> I actually do say what it can be: an offset in minutes from UTC,
> a string from the TZ database, or an implementation-defined alternative.
Err, you don't use the word "string", only "name". I was thinking of
something like:
 "If the implementation supports the tz database, and timezone is a
 string
  equaling a time zone name defined by that database, ..."
This allows implementations to accept other strings, which is probably
appropriate.

> 
> > (date->instant DATE)
> >   What happens if there is not enough info in DATE to uniquely
> >   determine an instant? Signal an error? Return #f?
> 
> Added "otherwise return #f".
That's clearly the Right Thing to do.
 
> > (date-field date FIELDNAME)
> >   Presumably FIELDNAME can be a symbol. Can it also be a string?
> 
> That would require an extra lookup at run time.  I think symbols are
> sufficient.
Agreed. How about adding "(a symbol)" to the spec? Like this:
 "Returns the numeric value of the field named fieldname (a symbol)
  within date ..."

> > (date-increment date fieldname increment)
<SNIP>
> Excellent wording; adopted.
 
> > The 'century' values in the ISO chronology don't seem right.
> > If 1965 AD has century=19 in ISO, then 33 AD must have century=0
> > so 43 BC would have century=-1, not 0.
> Fixed.
So (say) 43 BC is century -1 in Julian, Gregorian and ISO. Interesting.

While the Joda Time API looks pretty good on brief reading, the Scheme
version is much nicer -- yet another win for procedural APIs over
class-based programming.

Cheers ... Chris

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