Type Parameters:

E - the type of elements maintained by this stack
```
public interface PStack<E>
```
Persistent (functional) Stack.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`boolean`	`anyMatch(Predicate<E> predicate)`	Test given predicate on elements and return true if any of elements matches the predicate
`void`	`forEach(Consumer<E> action)`	Performs the given action for each element in this stack until all elements have been processed or the action throws an exception.
`boolean`	`isEmpty()`
`E`	`peek()`
`E`	`peek(int i)`
`PStack<E>`	`pop()`
`PStack<E>`	`push(E e)`
`int`	`size()`	Naive implementation has O(n) time complexity, where n is number of elements.
`String`	`toString()`

- Method Detail
  - push
```
PStack<E> push(E e)
```
    Returns:
    
    new stack with added element
  - peek
```
E peek()
```
    Returns:
    
    element at the top of this stack
    
    Throws:
    
    IllegalStateException - if this stack is empty.
  - peek
```
E peek(int i)
```
    Parameters:
    
    i - - index of element to be returned, 0 means top of the stack
    
    Returns:
    
    i-th element from top of the stack
    
    Throws:
    
    IllegalStateException - if stack has less than i elements
  - pop
```
PStack<E> pop()
```
    Returns:
    
    new stack with removed element
    
    Throws:
    
    IllegalStateException - if this stack is empty.
  - isEmpty
```
boolean isEmpty()
```
    Returns:
    
    true if this stack contains no elements
  - forEach
```
void forEach(Consumer<E> action)
```
    Performs the given action for each element in this stack until all elements have been processed or the action throws an exception.
  - anyMatch
```
boolean anyMatch(Predicate<E> predicate)
```
    Test given predicate on elements and return true if any of elements matches the predicate
    
    Parameters:
    
    predicate - predicate to be tested
    
    Returns:
    
    true if any of the stack elements satisfies the predicate
  - size
```
int size()
```
    Naive implementation has O(n) time complexity, where n is number of elements. More clever implementation could take advantage of PStack's immutability
    
    Returns:
    
    number of elements in the stack
  - toString
```
String toString()
```
    Overrides:
    
    toString in class Object
    
    Returns:
    
    a string representation of this stack

Interface PStack<E>

Method Summary

Method Detail

push

peek

peek

pop

isEmpty

forEach

anyMatch

size

toString