# Stack.3o - Man Page

Last-in first-out stacks.

Module   Stack

## Documentation

Module Stack
: sig end

Last-in first-out stacks.

This module implements stacks (LIFOs), with in-place modification.

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 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 : ('b -> 'a -> 'b) -> 'b -> 'a t -> 'b

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

### Iterators

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 iterator on the top of the stack.

Since 4.07

val of_seq : 'a Seq.t -> 'a t

Create a stack from the iterator

Since 4.07

## Info

2021-02-28 OCamldoc OCaml library