[bug#74689] [PATCH] Add predicates for decoded times and time deltas

[Paul Eggert]

On 12/28/24 07:56, Richard Lawrence wrote:
> I need to use
> `calendar-extract-month' with a plain date value, but
> `decoded-time-month' with a date-time value. I need type predicates to
> do such dispatching.

Not necessarily; you can instead try each function in turn and use the 
first that works.

I have some qualms about saying that decoded times are a "type". Whether 
a decoded time is valid depends on the timezone: (0 30 2 10 3 2024 0 t 
-21600) is a valid decoded time in Phoenix but not in Denver, because 
clocks sprang forward over that time in Denver but not in Phoenix. When 
data interpretation gets that complicated, the Emacs notion of "type" is 
not always the best.