Rounding of dates

There might be situations where we have a date/time and a need to compute the previous, or next complete time interval, for example, the next hour, or the previous day. The Dates API exposes a few methods for rounding Date and DateTime objects—floor, ceil, and time. They are quite intuitive and very powerful:

julia> now() 
2018-11-08T21:13:20.605 

# round down to the nearest hour 
julia> floor(now(), Hour) 
2018-11-08T21:00:00 

# or to the nearest 30 minutes increment 
julia> floor(now(), Minute(30))  
2018-11-08T21:00:00 

# it also works with dates  
julia> floor(today(), Month) # today() is the 8th of Nov 2018 
2018-11-01

The ceil function works similarly, but instead of rounding down, it rounds up. As for the round function, it will round up or down, depending on whichever is the closest value:

julia> round(today(), Month) 
2018-11-01 # today is the 11th so beginning of month is closer 
 
julia> round(today() + Day(10), Month) 
2018-12-01 # end of month...