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

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    (* Convert Unix timestamp to Date in SML *)
    val unix_timestamp = Time.fromSeconds 1721818631;
    val date = Time.toDate unix_timestamp;
    
    (* Extract the date components *)
    val year = Date.year date;
    val month = Date.month date;
    val day = Date.day date;
    val hour = Date.hour date;
    val minute = Date.minute date;
    val second = Date.second date;
    
    (* Print the result *)
    val _ = print ("Converted Date: " ^ Int.toString year ^ "-" ^
                    Int.toString (Date.monthToInt month) ^ "-" ^
                    Int.toString day ^ " " ^
                    Int.toString hour ^ ":" ^
                    Int.toString minute ^ ":" ^
                    Int.toString second ^ "\n");

Output:

Converted Date: 2024-07-24 10:57:11

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

Code Explanation

In this SML snippet Time.fromSeconds 1721818631 converts the Unix timestamp 1721818631 into an SML Time.time value. Time.toDate unix_timestamp converts this Time.time value into a Date.date structure. The components (year, month, day, etc.) are extracted using functions like Date.year, Date.month, Date.day, etc.
The month is converted to an integer using Date.monthToInt, and the result, 2024-07-24 10:57:11, is printed using print.

Convert Date to Unix timestamp 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