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more on precise date on ocaml

Dealing with "Precise" Dates

I already posted an article on (begining) playing with Dates on OCaml.

Preparing the Toplevel

As usual, we have to load and use several modules:

 #use "topfind";; #require "calendar";; 

Creating a Second

To create a second, the top reachable precision:

 CalendarLib.Time.Second.from_int 5;; 

Creating a Precise Date

To create a precise date, let's use the "make" function:

 CalendarLib.Fcalendar.Precise.make 2011 08 12 05 32 (float_of_int (CalendarLib.Time.Second.from_int 5));; CalendarLib.Fcalendar.Precise.make 2011 08 12 05 32 5.;; 

Create a Precise Period

When wanting to add 2 days to a date, we must use "The Date + 2 days Period". To create that "Period":

 CalendarLib.Fcalendar.Precise.Period.make 2011 08 12 05 32 (float_of_int (CalendarLib.Time.Second.from_int 5));; CalendarLib.Fcalendar.Precise.Period.make 2011 08 12 05 32 5.;; 

Make an operation (add)

Let's create a Date, and calculate the "two days later" Date:

 let d2 = CalendarLib.Fcalendar.Precise.add (CalendarLib.Fcalendar.Precise.make 2011 08 12 05 32 (float_of_int (CalendarLib.Time.Second.from_int 5))) (CalendarLib.Fcalendar.Precise.Period.make 0 0 2 0 0 (float_of_int (CalendarLib.Time.Second.from_int 0))) ;; let d2 = CalendarLib.Fcalendar.Precise.add (CalendarLib.Fcalendar.Precise.make 2011 08 12 05 32 5.) (CalendarLib.Fcalendar.Precise.Period.make 0 0 2 0 0 0.) ;; 
Then display it:
 CalendarLib.Printer.Precise_Fcalendar.to_string d2;; 

If the Date was from a string

I mostly intend to take the Date from an external source: A "date" field from a SQLite3 database, which is formatted "2011-08-16 16:00:01". To use it:

 let initiale = CalendarLib.Printer.Precise_Fcalendar.from_fstring "%F %T" "2011-08-16 16:00:01";; 
Then to add 2 days to it:
 let initiale_2 = CalendarLib.Fcalendar.Precise.add initiale (CalendarLib.Fcalendar.Precise.Period.make 0 0 2 0 0 (float_of_int (CalendarLib.Time.Second.from_int 0))) ;; 
Finally print it:
 CalendarLib.Printer.Precise_Fcalendar.to_string initiale_2;; 

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