Expand description


interim started as a fork, but ended up being a complete over-haul of chrono-english.

The API surface is the same, and all the original tests from chrono-english still pass, although there’s some key differences


Why use interim over chrono-english?

  1. chrono-english is not actively maintained: https://github.com/stevedonovan/chrono-english/issues/22
  2. interim simplifies a lot of the code, removing a lot of potential panics and adds some optimisations.
  3. supports no_std, as well as the time crate


  • std: This crate is no_std compatible. Disable the default-features to disable the std-lib features (just error reporting)
  • time: This crate is compatible with the time crate.
  • chrono: This crate is compatible with the chrono crate.

Supported Formats

chrono-english does absolute dates: ISO-like dates “2018-04-01” and the month name forms “1 April 2018” and “April 1, 2018”. (There’s no ambiguity so both of these forms are fine)

The informal “01/04/18” or American form “04/01/18” is supported. There is a Dialect enum to specify what kind of date English you would like to speak. Both short and long years are accepted in this form; short dates pivot between 1940 and 2040.

Then there are are relative dates like ‘April 1’ and ‘9/11’ (this if using Dialect::Us). The current year is assumed, but this can be modified by ‘next’ and ‘last’. For instance, it is now the 13th of March, 2018: ‘April 1’ and ‘next April 1’ are in 2018; ‘last April 1’ is in 2017.

Another relative form is simply a month name like ‘apr’ or ‘April’ (case-insensitive, only first three letters significant) where the day is assumed to be the 1st.

A week-day works in the same way: ‘friday’ means this coming Friday, relative to today. ‘last Friday’ is unambiguous, but ‘next Friday’ has different meanings; in the US it means the same as ‘Friday’ but otherwise it means the Friday of next week (plus 7 days)

Date and time can be specified also by a number of time units. So “2 days”, “3 hours”. Again, first three letters, but ‘d’,‘m’ and ‘y’ are understood (so “3h”). We make a distinction between second intervals (seconds,minutes,hours,days,weeks) and month intervals (months,years). Month intervals always give us the same date, if possible But adding a month to “30 Jan” will give “28 Feb” or “29 Feb” depending if a leap year.

Finally, dates may be followed by time. Either ‘formal’ like 18:03, with optional second (like 18:03:40) or ‘informal’ like 6.03pm. So one gets “next friday 8pm’ and so forth.


There are two entry points: parse_date_string and parse_duration. The first is given the date string, a DateTime from which relative dates and times operate, and a dialect (either Dialect::Uk or Dialect::Us currently.) The base time also specifies the desired timezone.

use interim::{parse_date_string, Dialect};
use chrono::Local;

let date_time = parse_date_string("next friday 8pm", Local::now(), Dialect::Uk)?;
println!("{}", date_time.format("%c"));

There is a little command-line program parse-date in the examples folder which can be used to play with these expressions.

The other function, parse_duration, lets you access just the relative part of a string like ‘two days ago’ or ‘12 hours’. If successful, returns an Interval, which is a number of seconds, days, or months.

use interim::{parse_duration, Interval};

assert_eq!(parse_duration("15m ago").unwrap(), Interval::Seconds(-15 * 60));


A collection of traits to abstract over date-time implementations


Error types for parsing and processing date/time inputs
Form of english dates to parse
A generic amount of time, in either seconds, days, or months.


Parse a date-time from the text, potentially relative to now. Accepts a Dialect to support some slightly different text parsing behaviour.
Parse an Interval from the text

Type Definitions