---
name: "Effect"
section: "3o"
platform: "linux"
package: "ocaml"
version: "5.5.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Effect"
---

# Effect(3o)

Effects.

## NAME

Effect - Effects.

## Module

Module   Effect

## Documentation

Module **Effect**\
  :  **sig end**

Effects.

See 'Language extensions/Effect handlers' section in the manual.

**Since** 5.0

**Alert unstable.** The Effect interface may change in incompatible ways in the future.

*type* **'a** *t* =  **'a eff** = ..

The type of effects.

*exception Unhandled* **:** **'a t** **-\>** **exn**

**Unhandled e** is raised when effect  **e** is performed and there is no handler for it.

*exception Continuation\_already\_resumed*

Exception raised when a continuation is continued or discontinued more than once.

*val perform* :  **'a t -\> 'a**

**perform e** performs an effect  **e** .

**Raises Unhandled** if there is no handler for  **e** .

*module Deep :* **sig end**

*module Shallow :* **sig end**