> ## Documentation Index
> Fetch the complete documentation index at: https://docs.forterulesengine.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Left

> v0.20.5

> **Left**\<`T`> = `object`

Defined in: [src/modules/types.ts:697](https://github.com/Forte-Service-Company-Ltd/forte-rules-engine-sdk/blob/40cc8388cecd8ee445b00b9df2b681cff8552ece/src/modules/types.ts#L697)

Either monad implementation for functional error handling

## Type Parameters

| Type Parameter |
| -------------- |
| `T`            |

## Properties

### left

> **left**: `T`

Defined in: [src/modules/types.ts:699](https://github.com/Forte-Service-Company-Ltd/forte-rules-engine-sdk/blob/40cc8388cecd8ee445b00b9df2b681cff8552ece/src/modules/types.ts#L699)

Left value

***

### right?

> `optional` **right**: `never`

Defined in: [src/modules/types.ts:701](https://github.com/Forte-Service-Company-Ltd/forte-rules-engine-sdk/blob/40cc8388cecd8ee445b00b9df2b681cff8552ece/src/modules/types.ts#L701)

Right value placeholder