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# then
Then is a minimalist plain text file calendar inspired by [When](https://www.lightandmatter.com/when/when.html). It has simple syntax optimized for the average scheduling case, but supports recurring cases more complex than most calendars. It optionally supports todo lists with deadlines as well.
Then is a single binary with no dependencies for text nerds who want to manage events directly in their text editor rather than a TUI/GUI. You can columnize, group, sort, and archive events/todos in your .then file(s) to keep them neat, pretty, and human readable.
In terms of features and complexity, Then lies between [When](https://www.lightandmatter.com/when/when.html) and [Remind](https://dianne.skoll.ca/projects/remind/) but aims to be less verbose than either.
# .then file syntax
```
# COMMENT
DATE, EVENT
- DETAILS
```
- Lines beginning with `#` are comments used to annotate or group events together.
- Lines beginning with `-` are additional details attached to the above event.
- Blank lines are ignored.
Otherwise, a line is an event. Everything before the first comma is interpreted as the date, which is a list of conditions separated by whitespace. Parameters can be written in any order. Short or long month and weekday names can be used.
## Example Syntax
```
# Common dates and recurrence
2025 Jul 17, Hike Mt. Fuji
Jan 1, New Year's Day (Jan 1 every year)
Tue, Taco night (Every Tuesday)
1, Mortgage due (1st of every month)
, Journal (Every day)
# Times
2025 Jan 1 00:00-03:00, Work party
2025 Jan 1 04:00, Go to bed
20:00 Fri, Friday Night Magic (Every Friday at 8pm)
9am, Coffee (Every day at 9am)
# Logic and Date Ranges
Mon Wed Fri, Submit TPS Report (Every Mon, Wed, or Fri)
Fri !13, Every Friday except the 13th
July 7-13 2024, Shark Week
(Jun 25 2025)-(Jul 4 2025), Japan Trip
# Uncommon recurrence patterns
J%3, Every third day
Fri 1W, First Friday of the month
# Combine multiple features for complex recurrence
Jul 10-19 2025 J%3-2, This event repeats July 10, 13, 16, 19
```
## Adding details to events
Any line starting with a `+` is attached to the nearest above event. This can be used for details about an event if you don't want to put everything on one line.
```
2025 Jan 5 16:00, Doctor's Appointment
+ 123 Gentoo Road, San Francisco, CA 12345
+ Dr. Elias Berkins, +1 (555)-123-1234
```
## Date Groups
You can put a day, month, and optionally year in parentheses to treat it as a single date. This lets you use the date for ranges and with the `!` operator like you'd expect.
```
Sun !(Dec 25), Every Sunday except Dec 25. The ! does NOT expand to !Dec !25.
(June 25 2025)-(Sep 1 2025), Summer vacation
(Jun 25)-(Sep 1) 2025, Alternative summer vacation
```
## Ranges (`-`)
You can specify ranges with a dash for days, weekdays, months, years, and date groups.
```
Mon-Fri, Work every weekday
Jan 1-7 2025, Las Vegas convention
(Jan 30 2025)-(Feb 3 2025), Ski trip
(Dec 25)-(Jan 2), Christmas vacation every year
```
You can omit one end of a date range to mean before or after a certain date.
```
Fri -(Sep 12 2025), Every Friday before (and including) Sep 12 2025
Fri (Sep 12 2025)-, Every Friday after (and including) Sep 12 2025
```
## Logic (AND, OR, NOT)
The date string is a list of conditions. Each condition of a different type (day, month, etc.) has to met for days the event takes place.
If multiple conditions of the same type exist, any of them can be satisfied.
Prepend any condition with `!` to mean NOT.
```
Fri Jan, Friday AND January (Every Fri in Jan)
1 15, 1st OR 15th
Fri !13, Friday, NOT the 13th
Sun !(Dec 25), Sunday, NOT December 25
2025 Aug 14, 2025 AND August AND the 14th
Sat Sun Aug, Saturday OR Sundays, in August
```
## First/last week(s) of Month (`W`, `L`)
xW is the xth set of 7 days of a month\
xL is the xth-from-last set of 7 days of a month
This is mostly useful for certain holidays and is analogous to the 'a' and 'b' parameters in When.
```
May 2W Sun, Mother's Day (Second Sunday of May)
May 1L Mon, Memorial Day (Last Monday of May)
1W Fri, First Friday (of every month)
```
## Time
You can express times in 24h format or AM/PM format like this. Your agenda will be sorted by the start time of events.
```
Fri 06:00, With no am/pm, 24h time is assumed
Fri 12:00am, Midnight
Fri 12pm, Noon
# You can include ranges if you'd like
Fri 05:00-06:00, Breakfast
Fri 12pm-1pm, Lunch
```
## Modified Julian Date (`J%x+y`) - Repeat every N days
Then supports using a Modified Julian Date as `J`. `J` is the number of days since midnight November 17, 1858. This can be used along with the modulo operator `%` to create complex recurring events.
This condition returns **true** when the result is 0. This is the opposite of how When works! Since you are always hunting zeros with this function it makes no sense to invert it every time.
```
J%3, Every third day
J%14-5, Every other Saturday
J%14+2, Every other Saturday (on the other weeks)
Sat J%2, Every other Saturday expressed in a different way
# You can use it for recurring reminders too
Jul 10-19 2025 J%3-2, This event repeats July 10, 13, 16, 19
```
Julian date modulus is definitely weird, but it's a concise way to express multiple uncommon recurring patterns without increasing program complexity and syntax vocabulary for features I virtually never use. Plus it's an homage to [When](https://www.lightandmatter.com/when/when.html), and I love When.
# Why would I use this?
Then was created to adapt existing CLI calendars to my personal workflow. Then is not only for the niche of people who use their terminal for scheduling, but for a sub-niche who prefer to edit a file over using a TUI which is why concise, legible syntax is so important. This is a very small group of people who virtually exclusively use [Remind](https://dianne.skoll.ca/projects/remind/). If you're happy with a web or phone calendar, Then probably won't change your mind.
Then has a few benefits over similar text file calendars:
1. **Then has the most concise syntax**. It minimizes special characters and simplifies ranges. Remind is arguably nicer for complex recurring cases and supports more types of conditions, but I rarely need these:
**Then**: `1, Water bill`\
**When**: `* * 1, Water bill`\
**Remind**: `REM 1 MSG Water bill`
**Then**: `Jul 1-7 2025, Vacation!`\
**When**: `m=Jul & d>=1 & d<=7 & y=2025, Vacation!`\
**Remind**: `REM Jul 1 2025 THROUGH Jul 7 2025 MSG Vacation!`
**Then**: `Jul 10-19 2025 J%3-2`\
**When**: `m=jul & d>=10 & d<=19 & y=2024 & !(j%3-2)`\
**Remind**: `REM Jul 10 2025 *3 THROUGH Jul 19 2025`
2. Then *optionally* can use an archive file to treat events like todos
Take the event "Change air filter", scheduled every 6 months. I might see that upcoming and archive this instance a week early, which removes it from my calendar. Or I might let it slide until next weekend, in which case it sticks around until it's done.
3. It *optionally* shows a todo list and upcoming deadlines.
# Alternatives
If you're interested in other text file calendars, I highly recommend When or Remind. It's easy to get caught up yak shaving the maximalist Emacs, so Org Mode has a very different vibe and I don't find it nearly as productive.
- [When](https://www.lightandmatter.com/when/when.html) - The simplest text file calendar that's flexible enough for real world use.
- [Remind](https://dianne.skoll.ca/projects/remind/) - The opposite: The most powerful, programmable calendar program ever made (CLI or otherwise) but simple cases are still concise.
- [Better overview here.](https://blog.thechases.com/posts/remind/)
- [Org Mode](https://orgmode.org) - An expansive productivity playground for text with agenda features, but also a time sink trap for tinkerers.
## See Also
- [khal](https://github.com/pimutils/khal) - Similar CLI calendar, but stores calendars directly as .ics files.
- TUI calendar/productivity apps like [Calcurse](https://calcurse.org/), [calcure](https://github.com/anufrievroman/calcure), and maybe [Taskwarrior](https://taskwarrior.org/).
- [Emacs Diary](https://www.gnu.org/software/emacs/manual/html_node/emacs/Format-of-Diary-File.html) - A single agenda/diary file.
- [Plain Text Personal Organizer](https://danlucraft.com/blog/2008/04/plain-text-organizer/)
- [Calendar.txt](https://terokarvinen.com/2021/calendar-txt/) - A one-day per line text calendar idea inspired by [todo.txt](https://todotxt.org/). Very simple but high maintenence due to lack of repeating events, etc.
# Todo
- Todos
- Todos with deadlines
- TUI
- Calendar output
- Color
- Julian modulus calculator (`then -j Jun 5 2025` > Outputs J and a table of common mod offsets)
- Android app
# License
MIT
|
