Get Today's Date using the Standard Library

Task

This recipe uses only the OCaml Standard Library.

The unix library, which ships with OCaml's standard library, provides functions to work with dates and times.

let today = Unix.localtime (Unix.time ());;
let day = today.Unix.tm_mday;;

Months are numbered 0 to 11.

let month = today.Unix.tm_mon + 1;;

Years are counted starting from 1900.

let year = today.Unix.tm_year + 1900;;

Printf.printf "The current date is %04d-%02d-%02d\n"
    year month day;;

Understanding Unix.localtime and Unix.time: The Unix.localtime function converts a timestamp obtained from Unix.time (which returns the current time since the Unix epoch) into a local time, represented by a tm structure. This structure includes fields like tm_year, tm_mon, and tm_mday for year, month, and day, respectively.
Month and Year Adjustments: In OCaml's Unix module, the month is zero-indexed (0 for January, 11 for December), and the year is the number of years since 1900. Don't forget to adjust these values to get a human-readable date.
Alternative Libraries: For more complex date-time operations, consider using external libraries like calendar or timedesc, which offer more functionalities like time zone handling and date arithmetic.