Thanks for sharing the description of your new functionality, at my
request in a GitHub issue <https://github.com/urweb/urweb/issues/220>!
It looks like there are no related strong opinions lurking on this
mailing list.
I would definitely be up to seeing appropriate types built into the
standard library (and compiler). Are there natural implementations for
the other major open-source SQL engines, not just Postgres?
On 8/16/20 9:56 AM, Simon Van Casteren wrote:
I've been building www.classy.school <http://www.classy.school> for
some time with Ur/Web now. It's an application for music schools and a
lot of it revolves around schedules: Who has lessons at what time,
which teacher, which room, etc etc.
In Ur/Web's "standard library" there are 2 types to represent dates /
times:
* Basis.time (Corresponds to unix epoch milliseconds IIRC). Contains
both date and time
* Datetime.t (Corresponds to a C struct IIRC). A bit more structure
than Basis.time
I don't work with these two types at all. I defined two other types:
* calendardate. This is actually a type synonym for Basis.time, but
only because it makes it possible to serialize this to sql values.
All operations on this type only change the date part, so year -
month - day. It contains no timezone info.
* clocktime: { Hour: int, Minute: int}. (I don't need seconds, but
it wouldn't hurt to add it as well). I have to serialize /
deserialize this whenever it goes into the DB, very annoying.
I've found this to be a much easier representation to work with for my
domain. Example: When you enroll with a teacher for some private
lessons, you often do it for x (eg: 10) lessons on a certain weekday
on a certain time. This time I have in my datamodel as a clocktime.
The actual "timestamps" of every lesson are seperate. Another benefit:
Comparing calendardates is much easier than comparing Basis.time /
Datetime.t.
Anyway, I've been thinking for some time to propose to upstream all of
this / some of this into the standard library, if there is any
interest for it. With that I'd also serialize them into the correct
PostgreSQL types (calendardate -> date, clocktime -> time without
timezone). Afterwards, I want to look into adding support for some SQL
operators on these, especially adding a clocktime to a date (which
then becomes a PostgreSQL timestamp without timezone, not sure yet how
to model this in the type system). Being able to do this in SQL would
be huge for my application.
So long story short, I'd mainly like to know if adding this stuff to
the standard library would be welcomed. If not, I'll keep all this in
my personal repo and put the SQL stuff in my urweb fork, but I thought
I'd ask :).
Simon
_______________________________________________
Ur mailing list
Ur@impredicative.com
http://www.impredicative.com/cgi-bin/mailman/listinfo/ur
