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

# Stdlib.Stack(3o)

no description

## NAME

Stdlib.Stack - no description

## Module

Module   Stdlib.Stack

## Documentation

Module **Stack**\
  :  **(module Stdlib\_\_Stack)**

Unsynchronized accesses

Unsynchronized accesses to a stack may lead to an invalid queue state. Thus, concurrent accesses to stacks must be synchronized (for instance with a  **Mutex.t** ).

*type* **!'a** *t*

The type of stacks containing elements of type  **'a** .

*exception Empty*

Raised when  **Stack.pop** or  **Stack.top** is applied to an empty stack.

*val create* :  **unit -\> 'a t**

Return a new stack, initially empty.

*val push* :  **'a -\> 'a t -\> unit**

**push x s** adds the element  **x** at the top of stack  **s** .

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

**pop s** removes and returns the topmost element in stack  **s** , or raises  **Stack.Empty** if the stack is empty.

*val pop\_opt* :  **'a t -\> 'a option**

**pop\_opt s** removes and returns the topmost element in stack  **s** , or returns  **None** if the stack is empty.

**Since** 4.08

*val drop* :  **'a t -\> unit**

**drop s** removes the topmost element in stack  **s** , or raises  **Stack.Empty** if the stack is empty.

**Since** 5.1

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

**top s** returns the topmost element in stack  **s** , or raises  **Stack.Empty** if the stack is empty.

*val top\_opt* :  **'a t -\> 'a option**

**top\_opt s** returns the topmost element in stack  **s** , or  **None** if the stack is empty.

**Since** 4.08

*val clear* :  **'a t -\> unit**

Discard all elements from a stack.

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

Return a copy of the given stack.

*val is\_empty* :  **'a t -\> bool**

Return  **true** if the given stack is empty,  **false** otherwise.

*val length* :  **'a t -\> int**

Return the number of elements in a stack. Time complexity O(1)

*val iter* :  **('a -\> unit) -\> 'a t -\> unit**

**iter f s** applies  **f** in turn to all elements of  **s** , from the element at the top of the stack to the element at the bottom of the stack. The stack itself is unchanged.

*val fold* :  **('acc -\> 'a -\> 'acc) -\> 'acc -\> 'a t -\> 'acc**

**fold f accu s** is  **(f (... (f (f accu x1) x2) ...) xn)** where  **x1** is the top of the stack,  **x2** the second element, and  **xn** the bottom element. The stack is unchanged.

**Since** 4.03

### Stacks and Sequences

*val to\_seq* :  **'a t -\> 'a Seq.t**

Iterate on the stack, top to bottom. It is safe to modify the stack during iteration.

**Since** 4.07

*val add\_seq* :  **'a t -\> 'a Seq.t -\> unit**

Add the elements from the sequence on the top of the stack.

**Since** 4.07

*val of\_seq* :  **'a Seq.t -\> 'a t**

Create a stack from the sequence.

**Since** 4.07