Std.DateTime

Date, time, and datetime types with formatting, parsing, and arithmetic.

Types

ParseError

type ParseError =
  | UnexpectedEnd
  | InvalidDigits String
  | UnexpectedChar (String, String)
  | UnknownSpecifier String
  | MissingField String
  deriving (Show, Debug, Eq)

Errors that can occur when parsing a datetime string.

Date

record Date {
  year: Int,
  month: Int,
  day: Int
}
  deriving (Show, Debug, Eq)

A calendar date (year, month, day).

Time

record Time {
  hour: Int,
  minute: Int,
  second: Int,
  microsecond: Int
}
  deriving (Show, Debug, Eq)

A time of day with microsecond precision.

NaiveDateTime

record NaiveDateTime {
  year: Int,
  month: Int,
  day: Int,
  hour: Int,
  minute: Int,
  second: Int,
  microsecond: Int
}
  deriving (Show, Debug, Eq)

A date and time without timezone information.

Effects

Clock

effect Clock {
  fun now : Unit -> NaiveDateTime
  fun today : Unit -> Date
  fun time_of_day : Unit -> Time
}

Effect for accessing the current wall-clock time.

Handlers

system_clock

handler system_clock for Clock

Handler that reads the system clock in UTC.

Functions

from_date_time

fun from_date_time : Date -> Time -> NaiveDateTime

Combines a Date and Time into a NaiveDateTime.

new

fun new : (year: Int) -> (month: Int) -> (day: Int) -> (hour: Int) -> (minute: Int) -> (second: Int) -> NaiveDateTime

Constructs a NaiveDateTime from individual components. Microsecond is set to 0.

to_date

fun to_date : NaiveDateTime -> Date

Extracts the date portion of a NaiveDateTime.

to_time

fun to_time : NaiveDateTime -> Time

Extracts the time portion of a NaiveDateTime.

format

fun format : String -> NaiveDateTime -> String

Format a NaiveDateTime using strftime-style specifiers. Supported: %Y (year), %m (month), %d (day), %H (hour), %M (minute), %S (second), %f (microsecond, 6 digits), %T (%H:%M:%S), %F (%Y-%m-%d), %b/%B (month name), %a/%A (weekday name), %% (literal %)

to_iso8601

fun to_iso8601 : NaiveDateTime -> String

Formats a NaiveDateTime as an ISO 8601 string ("YYYY-MM-DDTHH:MM:SS").

day_of_week

fun day_of_week : Date -> Int

Returns the day of the week (1 = Monday, 7 = Sunday).

is_leap_year

fun is_leap_year : Int -> Bool

Returns True if the given year is a leap year.

days_in_month

fun days_in_month : (year: Int) -> (month: Int) -> Int

Returns the number of days in the given month for the given year.

valid_date

fun valid_date : Date -> Bool

Returns True if the date is a valid calendar date.

add_seconds

fun add_seconds : Int -> NaiveDateTime -> NaiveDateTime

Adds the given number of seconds to a datetime.

add_days

fun add_days : Int -> NaiveDateTime -> NaiveDateTime

Adds the given number of days to a datetime.

add_hours

fun add_hours : Int -> NaiveDateTime -> NaiveDateTime

Adds the given number of hours to a datetime.

add_minutes

fun add_minutes : Int -> NaiveDateTime -> NaiveDateTime

Adds the given number of minutes to a datetime.

add_months

fun add_months : Int -> NaiveDateTime -> NaiveDateTime

Adds the given number of months to a datetime, clamping the day if needed.

add_years

fun add_years : Int -> NaiveDateTime -> NaiveDateTime

Adds the given number of years to a datetime.

diff_seconds

fun diff_seconds : NaiveDateTime -> NaiveDateTime -> Int

Returns the difference in seconds between two datetimes (a - b).

parse

fun parse : String -> String -> Result NaiveDateTime ParseError

Parse a datetime string using a strftime-style format. Supported: %Y, %m, %d, %H, %I, %p, %M, %S, %f (microseconds, 1-6 digits, right-padded), %b, %B, %F (%Y-%m-%d), %T (%H:%M:%S), %% (literal %). Numeric fields accept variable-width input (e.g. "%m" parses both "4" and "04").

from_iso8601

fun from_iso8601 : String -> Result NaiveDateTime ParseError

Parse an ISO 8601 datetime string ("YYYY-MM-DDTHH:MM:SS").