ValueOption<T>

This a type to represent the presence or absence of a T when it is a value type.

Operators

Implicit ValueOption<T> (T?)

Allows the client to set the T value to a ValueOption.

ValueOption<int> option = 1;
//option.IsSome = true

ValueOption<int> option = null;
//option.IsSome = false

Implicit T

Allows the client to get the T value from a ValueOption.

ValueOption<int> option = 1;
Console.Write(option);
//1

Implicit bool

Allows the client to know if a ValueOption contains value.

Option<int> option = 1;
if(option) 
    Console.WriteLine("Some");
else
    Console.WriteLine("None");
//"Some"

Properties

IsSome

Indicates if an ValueOption is Some, holding a T.

ValueOption<int> option = 1;
Console.WriteLine(option.IsSome);
//true

IsNone

Indicates if an Option is Nome, holding no value.

Option<int> option = ValueOption<int>.None();
Console.WriteLine(option.IsNome);
//true

Methods

static Some(T)

Returns an instance of ValueOption with T value.

var option = ValueOption.Some(10);
Console.Write(option);
//10

static None

Returns an instance of ValueOption with no Value.

var option = ValueOption.None();
Console.Write(option);
//throw a ValueOptionException

Bind<TResult> (Func<T, ValueOption<TResult>>)

Executes a given function over a ValueOption, taking its T value, and returning an ValueOption<TResult>.

ValueOption<int> option = 1;
ValueOption<bool> bound = option.Bind((r) => r > 0 ? true : false));
Console.Write(bound);
//true

Contains (T)

Verify if a ValueOption is Some and it’s T is equal to a given T. If so returns true otherwise returns false.

ValueOption<int> option1 = 1;
ValueOption<int> option2 = ValueOption<int>.None();
Console.Write(option1.Contains(option2));
//false

Count

Verify if an Option is Some. If so returns 1 otherwise returns 0.

ValueOption<bool> option = true;
Console.Write(option.Count());
//1

DefaultValue (T)

Returns T from a ValueOption if it is Some, otherwise returns the given default value.

var option = ValueOption<int>.None();
Console.Write(option.DefaultValue(25));
//25

DefaultWith (Func<T>)

Returns T from a ValueOption if it is Some, otherwise returns the result of the given function.

ValueOption<int> option = ValueOption<int>.None();
Console.Write(option.DefaultWith(() => 25));
//25

Exists (Func<T, bool>)

Verify if T matches a given predicate and returns true if so or false if not or ValueOption is None.

ValueOption<int> option = 1;
Console.Write(option.Exists((v) => v > 0));
//true

Filter (Func<ValueOption<T>, bool>)

Return the ValueOption itself if its None or the predicate is true, otherwise returns None.

ValueOption<int> option = 1;
var result = option.Filter((o) => o > 0));
//1

Flaten (ValueOption<ValueOption<T>>)

Returns T of the inner ValueOption instance if it is Some, otherwise None.

ValueOption<ValueOption<bool>> ValueOption<ValueOption<bool>>.Some(true);
Console.Write(option.Flaten());
//true

Fold (Func<TState, T, TState>, TState)

Updates and returns TState by the given function if ValueOption is Some, otherwise returns TState

ValueOption<int> option = 1;
Console.Write(option.Fold((s, t) => s + t), 10);
//11

FoldBack (Func<T, TState, TState>, TState)

As Fold but inverting T and TState as the given function parameters order.

ValueOption<int> option = 1;
Console.Write(option.FoldBack((r, s) => s + r), 10);
//11

ForAll (Func<T, bool>)

Verifies if ValueOption is None. If so returns true, otherwise applies the given function to T.

ValueOption<int> option = 1;
Console.Write(option.ForAll((r) => r > 10));
//false

Get

Returns the T if Some or throws an exception if None.

ValueOption<int> option = ValueOption<int>.None());
Console.Write(option.Get());
//throws ValueOptionException;

Iter (Action<T>)

Executes the given action if ValueOption is Some.

ValueOption<int> option = 1;
option.Iter(() => Console.Write("It's ok!"));
//"It's ok!"

Map (Func<T, ValueOption<T>>)

Returns the ValueOption itself if None or the result of the given function applied to T.

ValueOption<int> option = 1;
Console.Write(option.Map((r) => r > 0 ? true : false));
//true

Map2 (Func<ValueOption<T>>, Func<T, T, ValueOption<T>>)

Returns None if the Option itself and the first parameter Option are None, otherwise returns the result of the given function with the Option itself and the first parameter Option.

ValueOption<int> option1 = 1;
ValueOption<int> option2 = 2;
Console.Write(option1.Map2((o1, o2) => o1 == o2 ? o1 : 0));
//0

Match (Action<T>, Action)

Executes the first action based on T if ValueOption is Some or the second action if None.

ValueOption<int> option = 1;
option.Match((t) => Console.Write(t)), () => Console.Write("None"));
//1

OrElse (Option<T>)

Returns the ValueOption itself if Some or the first parameter.

var option = ValueOption<T>.None();
Console.Write(option.OrElse(2));
//2

OrElseWith (Func<Option<T>>)

Returns the Option itself if Some or the result of the given function.

var option = ValueOption<T>.None();
Console.Write(option.OrElseWith(() => 25)));
//25

ToArray

Returns an array with T if Option is Some, otherwise an empty one.

ValueOption<int> option = 1;
Console.Write(option.ToArray().Length);
//1

ToList

As ToArray but returns a generic list with T.

ValueOption<int> option = 1;
Console.Write(option.ToList().Count);
//1

ToValueOption

Returns Some if T is not null, or a None if so.

var myString = "Option!";
var option = myString.ToOption();
//Some ("Option!")