Apply

Creates a new Option<T> whose value is the result of applying the given applying function to Option<T>.Some value when both applying and option are IsSome.

Otherwise returns an Option<T>.None().

Parameters	Returns
Option<Func<T, TResult>> applying Option<T> option	Option<TResult>

Usage

This function is usually used to modify an option value by using an option function.

It works like a Map function, but in this case both value and the function are option values.

It's possible to use Apply function with two different syntaxes.

1. Apply<T, TResult>(function): in this case the function can be a regular function;

2. Apply(optionFunction): in this case the function needs to be a option function.

Expliciting an optional function

Func<int, int> multiply2 = value => value * 2;
Option<Func<int, int>> optionFunction = multiply2;

Option<int> optionValue = 4;
Option<int> result = optionValue.Apply(optionFunction);

//result.IsSome = true
//result.Some = 8

Using a regular function

Func<int, int> multiply2 = value => value * 2;

Option<int> optionValue = 4;
Option<int> result = optionValue.Apply<int,int>(multiply2);

//result.IsSome = true
//result.Some = 8

When the option function IsNone

Option<Func<int, int>> optionFunction = 
    Option<Func<int, int>>.None();

Option<int> optionValue = 4;
Option<int> result = optionValue.Apply(optionFunction);

//result.IsSome = false
//result.IsNone = true

When the option value IsNone

Func<int, int> multiply2 = value => value * 2;

Option<int> optionValue = Option<int>.None();
Option<int> result = optionValue.Apply<int,int>(multiply2);

//result.IsSome = false
//result.IsNone = true