Stack

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An immutable stack implementation. A stack is a LIFO (last-in-first-out) data structure where new values are added, retrieved, and removed from the end.

import Stack from "stack"

Types

Type declarations included in the Stack module.

Stack.Stack

type Stack<a>

Stacks are immutable data structures that store their data in a List.

Values

Functions and constants included in the Stack module.

Stack.make

make : () -> Stack<a>

Creates a new stack.

Returns:

type	description
`Stack<a>`	An empty stack

Stack.isEmpty

isEmpty : Stack<a> -> Bool

Checks if the given stack contains no items.

Parameters:

param	type	description
`stack`	`Stack<a>`	The stack to check

Returns:

type	description
`Bool`	`true` if the stack has no items or `false` otherwise

Stack.peek

peek : Stack<a> -> Option<a>

Provides the value at the top of the stack, if it exists.

Parameters:

param	type	description
`stack`	`Stack<a>`	The stack to inspect

Returns:

type	description
`Option<a>`	`Some(value)` containing the value at the top of the stack or `None` otherwise.

Stack.push

push : (a, Stack<a>) -> Stack<a>

Adds a new item to the top of the stack.

Parameters:

param	type	description
`value`	`a`	The item to be added
`stack`	`Stack<a>`	The stack being updated

Returns:

type	description
`Stack<a>`	A new stack with the item added to the end

Stack.pop

pop : Stack<a> -> Stack<a>

Removes the item at the top of the stack.

Parameters:

param	type	description
`stack`	`Stack<a>`	The stack being updated

Returns:

type	description
`Stack<a>`	A new stack with the last item removed

Stack.size

size : Stack<a> -> Number

Computes the size of the input stack.

Parameters:

param	type	description
`stack`	`Stack<a>`	The stack to inspect

Returns:

type	description
`Number`	The count of the items in the stack