# `Fraction`

An exact rational number as written, `3/4`: `1/2` and `2/4` are two values. `denominator` is at least 1.

[Maths and data](types.md#maths-and-data); not ordered; since Jadpo 0.1.0.

## Make one

Build one from its fields, `Fraction { numerator: ...  denominator: ... }`.

`text.parse(raw, as: Fraction)` reads one from its text; text that isn't one at all fails `malformed`, such as `3/0`, `3` or `3 / 4`.

## Fields

| Field | Type |
|---|---|
| `numerator` | `Int` |
| `denominator` | `Int` |

## Text, JSON and storage

`text.from` writes its canonical text, the one form `text.parse` reads back. JSON sends its canonical text as a string.

| Text | JSON |
|---|---|
| `3/4` | `"3/4"` |
| `-1/2` | `"-1/2"` |
| `30000/1001` | `"30000/1001"` |

It is stored in 2 columns, each named for the field, `_` and its suffix. This is `-1/2`:

| Column | Type | Holds |
|---|---|---|
| `<field>_numerator` | `bigint` | `-1` |
| `<field>_denominator` | `bigint` | `2` |

## Shown to people

`text.format(value, locale:)` shows it to people in their locale.

With `locale: Locale.en_gb`:

| Value | Shown |
|---|---|
| `3/4` | `3/4` |
| `-1/2` | `-1/2` |
| `30000/1001` | `30000/1001` |

## Operations

It has the contract's own operations: `text.parse`, `text.from`, `text.format`, `json.read`, `json.write` and `==`. It isn't ordered, so `<` and sorting don't take it. [Every standard type meets one contract](../topics/every-standard-type-meets-one-contract.md) says how they work.