Implement date functions

[baodrate]

Implement date functions:

• now
• fromdateiso8601
• todateiso8601

[baodrate]

todateiso8601 produces different formats depending on the input type:

• YYYY-MM-DDThh:mm:ss±hh:mm for ints
• YYYY-MM-DDThh:mm:ss.sssssssss±hh:mm for floats

I wanted to do the similar for fromdateiso8601 but wasn't happy with how bloated it made the function. Implementation suggestions would be appreciated

The other date functions (i.e. strftime/strptime) don't have equivalents in the time crate. Could maybe use https://github.com/MiSawa/time-fmt/

[01mf02]

I wanted to do the similar for fromdateiso8601 but wasn't happy with how bloated it made the function. Implementation suggestions would be appreciated

To help you with this, would you like to elaborate how you were trying to approach the problem?

The other date functions (i.e. strftime/strptime) don't have equivalents in the time crate. Could maybe use https://github.com/MiSawa/time-fmt/

I'd say let's go for now only for the ISO format, and postpone the hard case if there is sufficient demand later. :)

[baodrate]

To help you with this, would you like to elaborate how you were trying to approach the problem?

I don't remember exactly what I did, but it was pretty involved. Looking at it with fresh eyes, the problem seems a lot simpler. 😅 I added the new implementation in 7bc1b54. tell me what you think

[baodrate]

Looks like tests are failing because I added time as an optional dependency without properly feature-gating all the code, but I got a bit stuck on the best way to conditionally chain the datetime filters to the core filters:

jaq/jaq-core/src/core.rs

Lines 12 to 21 in 5184281

	pub fn core() -> impl Iterator<Item = (String, usize, Native)> {
	// TODO: make this more compact
	let core_run = CORE_RUN
	.iter()
	.map(|(name, arity, f)| (name.to_string(), *arity, Native::new(*f)));
	let core_update = CORE_UPDATE.iter().map(|(name, arity, run, update)| {
	(name.to_string(), *arity, Native::with_update(*run, *update))
	});
	core_run.chain(core_update)
	}

Should I just add time a non-optional dependency? Or should I go ahead and move all the code that depends on it behind feature-gates?

[01mf02]

You can go ahead and make time a non-optional dependency.
(For the same reason why regex is a non-optional dependency: I find it confusing if the set of available commands depends on features.)

[01mf02]

I don't remember exactly what I did, but it was pretty involved. Looking at it with fresh eyes, the problem seems a lot simpler. sweat_smile I added the new implementation in 7bc1b54. tell me what you think

That looks nice now that the functions round-trip.

[baodrate]

Just now realized that SystemTime requires std, which means now is a no-go. How do you think this case should be handled?

[01mf02]

Don't worry about std. I have a plan anyway to change the core filter implementation, and this will address the std issue.