Module format

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The one way Tilo shows dates, times, numbers, sizes and durations.

Every app and the shell format what a person reads through this module. It follows the person’s Region & Formats settings (date style, 12/24-hour clock, number style, first day of the week; region) and the desktop’s language (month and weekday names, word order, plurals), and it follows them live: a change re-renders every view without a restart (region::refresh). A policy check (tools/policy/check_formats.py) keeps hand-built formatting (strftime patterns, {:02}:{:02} clocks, ad-hoc size units) out of everything else.

The named styles:

Style	Function	English	German
list	`list_date`	`16:02`, `Yesterday`, `Sun`, `Jun 30`, `Jun 30, 2025`	`16:02`, `Gestern`, `So.`, `30. Juni`, `30. Juni 2025`
day fact	`day_fact`, `Formats::day_fact`	`Overdue`, `Today`, `Tomorrow`, `Thursday`, `Jun 29`; `Today 09:00`, `Thu 14:30`	`Überfällig`, `Heute`, `Morgen`, `Donnerstag`, `29. Juni`; `Heute 09:00`, `Do. 14:30`
moment fact	`moment_fact`, `Formats::moment_fact`	`15:00`, `Sat 09:00`, `Jun 29 09:00`	`15:00`, `Sa. 09:00`, `29. Juni 09:00`
timestamp	`timestamp`	`Jun 30, 2026, 13:42` (or ISO `2026-06-30 13:42`, …)	`30.06.2026, 13:42`
date	`date`	`Jun 30, 2026` (or ISO, US, EU, `30 Jun 2026`)	`30.06.2026` (or `30. Juni 2026`, Long)
time	`time`	`13:42` or `1:42 PM`	`13:42`
day heading	`day_heading`	`Tuesday, June 30`	`Dienstag, 30. Juni`
month heading	`month_heading`	`June 2026`	`Juni 2026`
relative	`relative`	`3 min ago`	`vor 3 Min.`
duration	`duration`	`1 hr 5 min`	`1 Std. 5 Min.`
timecode	`timecode`	`1:01:01`	`1:01:01`
size	`size`	`1.5 MB`	`1,5 MB`
memory	`memory`	`1.5 GiB`	`1,5 GiB`
rate	`rate`	`6.7 MB/s`	`6,7 MB/s`
count	`count`, `items`	`12,345`, `12 items`	`12.345`, `12 Objekte`
money	`money`	`$5`, `$0.42`, `$1,250`	`$5`, `$0,42`, `$1.250`
decimal	`decimal`	`3.14`	`3,14`

size uses SI decimal units and memory IEC binary ones, the platform’s rule shared with Files, Disks and the Storage pane: anything stored or transferred (files, downloads, caches, packages, drives, partitions) is a size and memory a memory, while a flow whose requirements are themselves stated in binary units (the installer’s GiB partition minimums) stays binary throughout so its numbers compare.

The free functions use the person’s current formats (Formats::current); the same styles on Formats take explicit formats and an explicit now, for tests and for callers formatting many values at once.

Modules§

region: The person’s region and formats, as every formatter reads them: the locale section of their settings (date style, 12/24-hour clock, number style, first day of the week) next to the desktop’s language.

Structs§

DayFact: A day as a person reads it: the words, and the tone they are read in.
Formats: One set of formats: the person’s RegionFormats. Words (month names, “Yesterday”, plurals) come from the language active on the calling thread.
NaiveDate: ISO 8601 calendar date without timezone. Allows for every proleptic Gregorian date from Jan 1, 262145 BCE to Dec 31, 262143 CE. Also supports the conversion from ISO 8601 ordinal and week date.
NaiveDateTime: ISO 8601 combined date and time without timezone.
NaiveTime: ISO 8601 time without timezone. Allows for the nanosecond precision and optional leap second representation.
RegionFormats: The formats a person chose in Region & Formats. number is None until they choose a number style; the language’s own convention applies then.
UnixSecs: Seconds since the Unix epoch, as protocols and files keep them.

Enums§

DateStyle: How dates render: the shared locale.date_format setting. The serde names are the exact strings the settings file uses (Language/ISO/US/EU/Long). Until the person picks one, dates follow the desktop’s language (DateStyle::Language); ISO is a choice like the others.
FirstDayOfWeek: The day a week starts on, for every calendar grid and week number.
NumberStyle: Decimal and grouping convention. Kept apart from the currency so someone can use EUR with either continental or English-language formatting.
Period: A span of the calendar a view shows: one day, a run of days, or a month.
Weekday: The day of week.

Traits§

Moment: A moment the formatters can show: a chrono date and time in any zone, a local NaiveDateTime or UnixSecs.

Functions§

arithmetic_operator: The arithmetic operator a typed symbol stands for: a keypad shows the multiplication and division signs where the expression grammar uses * and /.
capitalize_first: Upper-case the first character (by Unicode case mapping, so ß becomes SS) and keep the rest unchanged.
compact_count: Abbreviate a large count to at most one fractional digit: 1.2K, 3.4M, 1.1B. Exact tenths omit the redundant .0 (12K, not 12.0K) and a value that rounds into the next unit is promoted (999_999 becomes 1M, never 1000.0K). Values below 1000 print in full.
count: The count style: 12,345. See Formats::count.
date: The date style: Jun 30, 2026 by default. See Formats::date.
date_of: The date style for a moment’s local calendar day.
day_done: Formats::day_done against today: the heading over what was done on day, in the person’s formats and the desktop’s language.
day_done_today: day_done against the person’s own today (crate::clock::today).
day_fact: The day fact day_fact_today holds, against today: the person’s formats, the language’s words.
day_fact_today: day_fact against the person’s own today (crate::clock::today): the one call a surface makes when it shows a date fact.
day_heading: The day heading style: Tuesday, June 30. See Formats::day_heading.
day_heading_short: The short day heading: Tue, Jun 30. See Formats::day_heading_short.
day_range: A span of days: Jun 23 – 29. See Formats::day_range.
decimal: The decimal style: 3.14. See Formats::decimal.
duration: The duration style: 1 hr 5 min. See Formats::duration.
first_weekday: The first day of the week the person chose.
items: A count of things: 12 items. See Formats::items.
list_date: The list style for at, relative to now: 16:02, Yesterday, Sun, Jun 30, Jun 30, 2025. See Formats::list_date.
memory: The memory style: 5 MiB. See Formats::memory.
moment_fact: The moment fact style for a moment: a time of day, with the short weekday before it when it is not today. See Formats::moment_fact.
money: An amount in millionths of the currency: $5, $0.42, $1,250. See Formats::money.
month_day: Month and day: Jun 30.
month_day_time: A day without its year and a time of day: Jun 30, 14:05. See Formats::month_day_time.
month_day_year: Month, day and year with the month named: Jun 30, 2025.
month_heading: The month heading style: June 2026.
month_heading_short: A month in a tight space: Jun 2026.
month_name: The month’s name (1 = January): June.
month_short: The abbreviated month (1 = January): Jun.
near_day: Name a calendar day next to today in the host’s language — Yesterday, Today, Tomorrow — or None further out, where the caller shows its own date. days_from_today is negative for the past.
parse_money: The millionths of the currency an amount a person typed names: 5, 0.50, 12.5 or $5, read the way money writes them.
percent: A percentage of fraction (0.0..=1.0), whole: 42%.
range: Any span between two formatted values: Mon, Jun 29 – Sun, Jul 5, 9:00 – 10:30.
rate: A transfer rate: 6.7 MB/s. See Formats::rate.
relative: The relative style: a past interval (in seconds) as a coarse label in the host’s language: just now, 3 min ago, 2 hr ago, yesterday, 4 days ago, 2 weeks ago, 3 months ago, 1 year ago. Zero and negative deltas (clock skew) read just now. Counts go through Fluent plurals, so each language words its own singular and plural forms.
relative_ahead: The relative style ahead: a future interval (in seconds) as a coarse label in the host’s language: in a moment, in 3 min, in 2 hr, tomorrow, in 4 days, in 2 weeks, in 3 months, in 1 year. Zero and negative deltas read in a moment.
relative_compact: The relative style for list columns too tight for relative’s wording: now, 3m, 2h, 4d, 2w, 3mo, 1y. Zero and negative deltas (clock skew) read now.
size: The size style: 1.5 MB. See Formats::size.
time: A time of day: 14:05 or 2:05 PM.
time_of: The time of day of a moment: 14:05 or 2:05 PM.
timecode: The timecode style, for media positions and lengths: m:ss under an hour, h:mm:ss from one hour.
timestamp: The timestamp style: Jun 30, 2026, 13:42 by default. See Formats::timestamp.
week: The seven weekdays from the first day of the week the person chose.
weekday_name: The weekday’s name: Sunday.
weekday_short: The abbreviated weekday: Sun.

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Modules§

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