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> I prefer time-comparison names without terminal question marks.
> I think these
> (time= t1 t2)
> (time< t1 t2)
> are clearer than these
> (time=? t1 t2)
> (time<? t1 t2)
> The terminal ? is redundant, hence unnecessary clutter.
But so is string=?, char=?, etc. Here I prefer consistency with RnRS
than independent elegance because you don't have to constantly wonder
if you should add the question mark or not. (But I agree that dropping
the ? is more elegant.)
Yes, you have a point. But let us move forward -- I'd like to lobby
for starting a *new* convention. No irritating terminal ?'s on comparison
functions -- <=, <, =, >, >= predicates.
> You may wish to look at the scsh time spec, at the above URL. It has some
> flaws, due to its close binding to the Posix API, but also has some
> nice features. There are two time representations -- time (seconds), and
> date (broken-out time -- y/m/d/h/m/s etc.) The API is quite simple:
> (date) -> the current date (a struct)
> (date tm [tz]) -> the date for time TM in timezone TZ
> (time) -> the current time (an integer)
> (time dt) -> the time for date DT
Except for the names (I would prefer (current-date) and
(current-time)) and that time is represented concretely by an integer,
I like this approach. To me a "time" object is an absolute point on
the time line, and is independent of time zones, etc (and also
independent of relativity but that's another topic...).
A "date" object is really a representation of time that depends on local
context (the time zone, daylight-savings time, etc).
However, if you use the names CURRENT-DATE & CURRENT-TIME, you can't make
each function work as both the current-time fetcher and converter with
optional arguments, as I did. I think using DATE & TIME makes for a very
small, simple interface. You simply use the name corresponding to the kind
of thing you want; if you are doing a conversion, then you give the parameter.
End of story.
Making time a distinct datatype, instead a number, has plusses & minusses.
I have mixed feelings.
Increased error detection
Can represent time as pair of ints -- second & subsecond precision.
...which allows hiding leap seconds in the subsecond part, a la
Cannot use arithmetic ops to do time calculations -- very annoying
Must cons to generate a time; not low overhead.
The second minus -- that you must allocate storage to get a time stamp -- is
not *so* important, because you can always have an alternate, purpose-designed
low-overhead interface, of the TIME+TICKS variety, which can return what
Markus Kuhn calls "process" time.
However, I'm not so comfortable with the first minus. Is there to be some
form of conversion between time & seconds?
I suggest there are enough open issues to warrant extending the discussion
period of this SRFI. Time is tricky.