> For the complete documentation index, see [llms.txt](https://docs.rainbird.ai/rainbird/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.rainbird.ai/rainbird/knowledge-modelling/modelling-features/rblang-reference/functions-reference.md).

# Functions reference

Use these functions inside `expression` conditions.

For UI-focused examples, see [Expressions List](/rainbird/knowledge-modelling/modelling-features/relationships/rules/expressions-list.md).

### Comparison

Use comparison functions to return `true` or `false`.

* `is equal to`
* `is not equal to`
* `is greater than`
* `is greater than or equal to`
* `is less than`
* `is less than or equal to`
* `isWithinRange(val, min, max)`

Examples:

```xml
<condition expression="%AGE is greater than 30"/>
<condition expression="isWithinRange(%AGE, 18, 35)"/>
```

### String

Use string functions for matching and text construction.

* `includes(str, substr)`
* `startsWith(str, prefix)`
* `endsWith(str, suffix)`
* `regexCount(str, pattern)`
* `+` for concatenation

For `regexCount()`, the pattern must be a JavaScript-flavoured (ECMAScript) regex in `/pattern/flags` format.

Example: `'/cat/gi'`

Examples:

```xml
<condition expression="includes(%TEXT, 'cat')"/>
<condition expression="'Status: ' + %NAME" value="%O"/>
```

### Mathematical

Use math functions with number values.

* `+`, `-`, `*`, `/`
* `round(num, decimals)`
* `ceil(num)`
* `floor(num)`
* `abs(num)`
* `min(n1, n2, ...)`
* `max(n1, n2, ...)`
* `mod(num, divisor)`
* `pow(base, exp)`
* `sqrt(num)`

Example:

```xml
<condition expression="round((%SCORE_1 + %SCORE_2) / 2, 2)" value="%O"/>
```

### Date

Use date functions with `date` concepts and date literals.

* `today()`
* `now()`
* `dayOfWeek(date)`
* `dayOfMonth(date)`
* `dayOfYear(date)`
* `monthOfYear(date)`
* `year(date)`
* `addDays(date, n)`
* `subtractDays(date, n)`
* `addWeeks(date, n)`
* `addMonths(date, n)`
* `addYears(date, n)`
* `daysBetween(d1, d2)`
* `weeksBetween(d1, d2)`
* `monthsBetween(d1, d2)`
* `yearsBetween(d1, d2)`
* `isBeforeDate(d1, d2)`
* `isSameDate(d1, d2)`
* `isAfterDate(d1, d2)`

Use date strings in `YYYY-MM-DD` or `YYYY-MM-DDTHH:MM:SS` format.

### List

List functions work over relationship instances. They are most useful with plural relationships.

Use `*` for `all` or variables and literals to filter the subject or object values used by the function.

* `countRelationshipInstances(subject, relationship, object)`
* `sumObjects(subject, relationship, object)`
* `minObjects(subject, relationship, object)`
* `maxObjects(subject, relationship, object)`
* `joinObjects(subject, relationship, object)`
* `isSubset(subject1, relationship1, object1, subject2, relationship2, object2)`

Examples:

```xml
<condition expression="countRelationshipInstances(%S, 'purchased product', *)" value="%COUNT"/>
<condition expression="sumObjects(%S, 'has score', *)" value="%SUM"/>
```

### Logical operators

Use `and` and `or` to combine tests.

```xml
<condition expression="(%AGE >= 25) and (%AGE <= 40)"/>
<condition expression="(%AGE < 25) or (%AGE > 60)"/>
```

Use parentheses to control evaluation order.


---

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