# `InstantRange`

The moments from a start up to, but not including, an end.

Use it for a shift or a meeting slot. Because the end is left out, one slot can start exactly when the last one ends. For whole days, use [`DateRange`](/docs/types/type-date-range.md).

## Shape

| Field | Type | Required? |
|---|---|---|
| `start` | [`Instant`](/docs/types/type-instant.md) | Yes |
| `end` | [`Instant`](/docs/types/type-instant.md) | Yes |

Its parts keep these rules, and a value that breaks one fails with the rule's name:

- `start_not_after_end`: start <= end

## Example

```jadpo
InstantRange { start: "2026-10-25T09:00:00Z" end: "2026-10-25T17:00:00Z" }
```

`text.parse(raw, as: InstantRange)` reads one from text that comes from outside. Text that isn't one at all fails `malformed`, such as `2026-10-25T09:00:00Z` or `2026-10-25T09:00:00Z/tomorrow`.

These operations give one: `range.intersection`, `temporal.day_bounds`, `temporal.month_bounds`, `temporal.week_bounds` and `temporal.year_bounds`.

## Good to know

- `start` can't come after `end`.
- `temporal.day_bounds` gives the range of a whole day in a [`Zone`](/docs/types/type-zone.md).
- `==` tells you whether two are the same. `<` and `list.sort_by` don't take it, so sort by one of its parts instead.

## In JSON

An object of its parts, in a request, a response or `json.write`:

```json
{"start":"2026-10-25T09:00:00Z","end":"2026-10-25T17:00:00Z"}
```

## Details

<details>
<summary>Text form, storage, how it is shown, and operations</summary>

`InstantRange` is in the group Time and calendar, and has been in Jadpo since 0.1.0.

### Text form

`text.from` writes one standard text form, the same form `text.parse` reads back: `2026-10-25T09:00:00Z/2026-10-25T17:00:00Z`.

### How it is stored

It is stored in one column named for the field, of type `tstzrange`. `2026-10-25T09:00:00Z/2026-10-25T17:00:00Z` is stored as `tstzrange('2026-10-25 09:00:00.000000+00'::timestamptz, '2026-10-25 17:00:00.000000+00'::timestamptz, '[)')`.

### How it is shown to people

`text.format(value, locale:)` shows it to people in their locale. A call also gives `zone:` and `format:`.

With `locale: Locale.en_gb`, `zone: Zone.europe_london` and `format: TimeFormat.date_time_medium`:

| Value | Shown |
|---|---|
| `2026-10-25T09:00:00Z/2026-10-25T17:00:00Z` | `25 Oct 2026, 09:00:00 – 25 Oct 2026, 17:00:00` |

### Operations

- `range.contains(range: Range<T>, value: T) -> Bool`: Whether `value` is inside `range`.
- `range.intersection(a: Range<T>, b: Range<T>) -> Range<T>?`: The part `a` and `b` share; `none` when they don't overlap.
- `range.overlaps(a: Range<T>, b: Range<T>) -> Bool`: Whether `a` and `b` share at least one value.
- `temporal.day_bounds(date: CalendarDate, zone: Zone) -> InstantRange`: The instants `date` runs between in `zone`: 23, 24 or 25 hours.
- `temporal.month_bounds(date: CalendarDate, zone: Zone) -> InstantRange`: The month holding `date` in `zone`.
- `temporal.week_bounds(date: CalendarDate, zone: Zone, starts_on: Weekday) -> InstantRange`: The week holding `date` in `zone`, starting on `starts_on`.
- `temporal.year_bounds(date: CalendarDate, zone: Zone) -> InstantRange`: The year holding `date` in `zone`.

It also takes `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. [How every standard type behaves](/docs/every-standard-type-meets-one-contract.md) says how they work.

</details>