3 ms·

On a side but related note, I don't understand why many programming languages and databases don't have a positive and negative infinity date placeholder/token v

On a side but related note, I don't understand why many programming languages and databases don't have a positive and negative infinity date placeholder/token value that is standardized and cross platform. Negative infinity date is "past", positive infinity date is "future". This would solve the common problem of what date to use when you are trying to talk about unknown date in the future or unknown date in the past, rather than using weird placeholders like 9999-12-31 or 1900-01-01 or other magic numbers.

rwallace 10y ago
There are lots of scenarios where you need to represent an unknown/indefinite date, but this can be done with null; are there any reasonably common scenarios where you need to distinguish between unknown past and unknown future in the same context?
- sixdimensional 10y ago
  I agree, null is often chosen as an option. But null is also not a value by definition so then it becomes hard to do a range check when using say, a start and end date. Also, what is the difference between a date in the future and null? Semantics I think-a token future date has an explicit value, whereas if you use NULL, the use of that as a future date has a new implicit value that depends on context. I know maybe it sounds pedantic or perhaps out there but I think that token dates that are fixed and specified as positive or negative infinity gives a mathematical value that can then be reasoned with formulaically, just like we do with calculus. We keep running into finite limits which is what keeps causing problems such as Y2K, Y2K38, the beginning of Unix time (1970-1-1) - maybe if we treated the beginning and end of time as infinity some new method of reasoning about dates would become more apparent. I'm not sure as I haven't gone all the way down the rabbit hole with this idea yet.
  - sixdimensional 10y ago
    Another thought - if you treat a date as a relative variable related to a frame of reference (example, what if you defined the future to be a token value of today + N days, which means it is always calculated as a dynamic future date ahead of today), maybe we could reason about relative past and present using relative variable dates? Or maybe this is just crazy talk.
- sixdimensional 10y ago
  So, not a common case, but how about when trying to schedule an event dynamically that starts on an unknown date in the future and lasts for N days beyond that?
- caf 10y ago
  Distinguishing between "unknown past" and "unknown future" is helpful if you're going to be sorting things on date.
ekimekim 10y ago
In languages where epoch time is generally represented as float, inf and -inf do what you describe.

rwallace 10y ago

There are lots of scenarios where you need to represent an unknown/indefinite date, but this can be done with null; are there any reasonably common scenarios where you need to distinguish between unknown past and unknown future in the same context?

sixdimensional 10y ago
I agree, null is often chosen as an option. But null is also not a value by definition so then it becomes hard to do a range check when using say, a start and end date. Also, what is the difference between a date in the future and null? Semantics I think-a token future date has an explicit value, whereas if you use NULL, the use of that as a future date has a new implicit value that depends on context. I know maybe it sounds pedantic or perhaps out there but I think that token dates that are fixed and specified as positive or negative infinity gives a mathematical value that can then be reasoned with formulaically, just like we do with calculus. We keep running into finite limits which is what keeps causing problems such as Y2K, Y2K38, the beginning of Unix time (1970-1-1) - maybe if we treated the beginning and end of time as infinity some new method of reasoning about dates would become more apparent. I'm not sure as I haven't gone all the way down the rabbit hole with this idea yet.
- sixdimensional 10y ago
  Another thought - if you treat a date as a relative variable related to a frame of reference (example, what if you defined the future to be a token value of today + N days, which means it is always calculated as a dynamic future date ahead of today), maybe we could reason about relative past and present using relative variable dates? Or maybe this is just crazy talk.
sixdimensional 10y ago
So, not a common case, but how about when trying to schedule an event dynamically that starts on an unknown date in the future and lasts for N days beyond that?
caf 10y ago
Distinguishing between "unknown past" and "unknown future" is helpful if you're going to be sorting things on date.

ekimekim 10y ago

In languages where epoch time is generally represented as float, inf and -inf do what you describe.