Simplify LocalDate(Time) constructor parameter names

The parameter names are very weird for day-to-day use:

LocalDateTime(year = 2021, monthNumber = 1, dayOfMonth = 1, hour = 12)

I don’t care that month is a number. That’s what we have a type system for. OfMonth for day is also redundant as that’s obvious from the context.

https://github.com/Kotlin/kotlinx-datetime/blob/3af71d2e874592fc70282de441a09d024dcefb54/core/common/src/LocalDateTime.kt#L50

[ilya-g]

I believe that numbering months from zero is an abomination and should not be considered a normal practice that we take into account when naming the corresponding parameter/property.

[dkhalanskyjb]

You make a good point about dayOfMonth. I agree, nobody will be confused about the meaning of LocalDateTime.day.

Regarding monthNumber, Month is a nice, well-typed, unambiguous thing. monthNumber: Int, on the other hand, is not. Unfortunately, many systems use zero-based numbering for months, even while using one-based numbering for days. JavaScript comes to mind:

new Date(2020, 1, 1) Date Sat Feb 01 2020 00:00:00 GMT+0100 (Central European Standard Time)

So, it makes sense for LocalDate(Time)? to highlight an area that would give potentially misleading results by using a longer name. “monthNumber? What kind of a number? The usual kind, 1…12, or zero-based?” If we manage to provoke a question of this kind, we have won.

In your example (which, I assume, is simplified, but nonetheless), Month.DECEMBER is, I think, a better choice, which should be more obvious with a less prominent month number, like 5 or 10.

WDYT?