com.aol.cyclops.lambda.utils

Class LazyImmutable<T>

java.lang.Object

com.aol.cyclops.lambda.utils.LazyImmutable<T>

Type Parameters:

T -

All Implemented Interfaces:

java.util.function.Supplier<T>

public class LazyImmutable<T>
extends java.lang.Object
implements java.util.function.Supplier<T>

A class that represents an 'immutable' value that is generated inside a lambda expression, but is accessible outside it It will only allow it's value to be set once. Unfortunately the compiler won't be able to tell if setOnce is called more than once example usage

 public static <T> Supplier<T> memoiseSupplier(Supplier<T> s){
		LazyImmutable<T> lazy = LazyImmutable.def();
		return () -> lazy.computeIfAbsent(s);
	}
 

Has map and flatMap methods, but is not a Monad (see example usage above for why, it is the initial mutation that is valuable).

Constructor Summary

Constructors

Constructor and Description
LazyImmutable()

Method Summary

Modifier and Type	Method and Description
T	computeIfAbsent(java.util.function.Supplier<T> lazy) Get the current value or set if it has not been set yet
static <T> LazyImmutable<T>	def()
<R> LazyImmutable<R>	flatMap(java.util.function.Function<T,LazyImmutable<R>> fn) FlatMap the value stored in Immutable Closed Value from one Value to another If this is an unitiatilised ImmutableClosedValue, an uninitialised closed value will be returned instead
T	get()
<R> LazyImmutable<R>	map(java.util.function.Function<T,R> fn) Map the value stored in this Immutable Closed Value from one Value to another If this is an unitiatilised ImmutableClosedValue, an uninitialised closed value will be returned instead
static <T> LazyImmutable<T>	of(T value)
LazyImmutable<T>	setOnce(T val) Set the value of this ImmutableClosedValue If it has already been set will throw an exception
static <T> LazyImmutable<T>	unbound() Create an intermediate unbound (or unitialised) ImmutableClosedValue)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LazyImmutable

public LazyImmutable()

Method Detail

get

public T get()

Specified by:

get in interface java.util.function.Supplier<T>

Returns:

Current value

unbound

public static <T> LazyImmutable<T> unbound()

Create an intermediate unbound (or unitialised) ImmutableClosedValue)

Returns:

unitialised ImmutableClosedValue

of

public static <T> LazyImmutable<T> of(T value)

Parameters:

value - Create an initialised ImmutableClosedValue with specified value

Returns:

Initialised ImmutableClosedValue

def

public static <T> LazyImmutable<T> def()

Returns:

a defined, but unitialised LazyImmutable

map

public <R> LazyImmutable<R> map(java.util.function.Function<T,R> fn)

Map the value stored in this Immutable Closed Value from one Value to another If this is an unitiatilised ImmutableClosedValue, an uninitialised closed value will be returned instead

Parameters:

fn - Mapper function

Returns:

new ImmutableClosedValue with new mapped value

flatMap

public <R> LazyImmutable<R> flatMap(java.util.function.Function<T,LazyImmutable<R>> fn)

FlatMap the value stored in Immutable Closed Value from one Value to another If this is an unitiatilised ImmutableClosedValue, an uninitialised closed value will be returned instead

Parameters:

fn - Flat Mapper function

Returns:

new ImmutableClosedValue with new mapped value

setOnce

public LazyImmutable<T> setOnce(T val)
                         throws LazyImmutableSetMoreThanOnceException

Set the value of this ImmutableClosedValue If it has already been set will throw an exception

Parameters:

val - Value to set to

Returns:

Current set Value

Throws:

LazyImmutableSetMoreThanOnceException

computeIfAbsent

public T computeIfAbsent(java.util.function.Supplier<T> lazy)

Get the current value or set if it has not been set yet

Parameters:

lazy - Supplier to generate new value

Returns:

Current value