How to convert Datetime to Unix timestamp in SML (Standard ML)

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    (* Convert Date to Unix timestamp in SML *)
    val date = Date.fromTime (2018, Date.Jan, 1, 0, 0, 0);  (* 2018-01-01 00:00:00 *)
    val unix_timestamp = Time.toSeconds (Date.toTime date);
    
    (* Print the Unix timestamp *)
    val _ = print ("Unix Timestamp: " ^ Int.toString unix_timestamp ^ "\n");

Output:

Unix Timestamp: 1514764800

Example only. There may be multiple ways to perform this operation.

Code Explanation

In this SML date to Unix timestamp conversion snippet Date.fromTime (2018, Date.Jan, 1, 0, 0, 0) creates a Date.date structure representing '2018-01-01 00:00:00'. Date.toTime date converts the Date.date structure into a Time.time value. Time.toSeconds (Date.toTime date) converts the Time.time value to the Unix timestamp, which is printed using print.

Convert Unix timestamp to Date in Sml

Other useful SML (Standard ML) date functions

Function	Description	Example
`Time.fromSeconds()`	Converts an integer (Unix timestamp in seconds) to a `Time.time` value.	`Time.fromSeconds 1514764800` returns a Time.time value representing 2018-01-01 00:00:00
`Time.toDate()`	Converts a `Time.time` value to a `Date.date` structure.	`Time.toDate (Time.fromSeconds 1514764800)` returns the date 2018-01-01 00:00:00
`Time.toSeconds()`	Converts a `Time.time` value to a Unix timestamp (in seconds).	`Time.toSeconds (Date.toTime date)` returns the Unix timestamp 1514764800
`Date.fromTime()`	Creates a `Date.date` structure from year, month, day, hour, minute, and second.	`Date.fromTime (2018, Date.Jan, 1, 0, 0, 0)` returns 2018-01-01 00:00:00
`Date.toTime()`	Converts a `Date.date` structure to a `Time.time` value.	`Date.toTime (Date.fromTime (2018, Date.Jan, 1, 0, 0, 0))` returns a Time.time value for 2018-01-01 00:00:00
`Date.year()`	Extracts the year from a `Date.date` structure.	`Date.year (Date.fromTime (2018, Date.Jan, 1, 0, 0, 0))` returns 2018
`Date.month()`	Extracts the month from a `Date.date` structure.	`Date.month (Date.fromTime (2018, Date.Jan, 1, 0, 0, 0))` returns Date.Jan
`Date.day()`	Extracts the day of the month from a `Date.date` structure.	`Date.day (Date.fromTime (2018, Date.Jan, 1, 0, 0, 0))` returns 1
`Date.hour()`	Extracts the hour from a `Date.date` structure.	`Date.hour (Date.fromTime (2018, Date.Jan, 1, 0, 0, 0))` returns 0
`Date.minute()`	Extracts the minute from a `Date.date` structure.	`Date.minute (Date.fromTime (2018, Date.Jan, 1, 0, 0, 0))` returns 0
`Date.second()`	Extracts the second from a `Date.date` structure.	`Date.second (Date.fromTime (2018, Date.Jan, 1, 0, 0, 0))` returns 0

Current Unix Timestamp SECONDS SINCE JAN 01 1970

Current UTC Time

2025-08-20