/// <summary>
/// Returns the <paramref name="option"/> if it <see cref="Option{T}.IsSome"/> and the <paramref name="predicate"/> return true when applied it.
/// Otherwise, returns an <see cref="Option{T}.None()"/>.
/// </summary>
/// <typeparam name="T">The type of the option value.</typeparam>
/// <param name="predicate">A function that evaluates whether the value contained in the option should remain, or be filtered out.</param>
/// <param name="option">The input option.</param>
/// <returns>
/// Returns <paramref name="option"/> if the option <see cref="Option{T}.IsSome"/> and the <paramref name="predicate"/> function returns true.
/// Otherwise, returns an <see cref="Option{T}.None()"/>.
/// </returns>
public static Option <T> Filter <T>(this Option <T> option, Func <T, bool> predicate)
=> OptionModule.Filter(predicate, option);
/// <summary>
/// Returns true if the <paramref name="option"/> <see cref="Option{T}.IsSome"/> and the <paramref name="predicate"/> return true when applied it.
/// Otherwise, returns false.
/// </summary>
/// <typeparam name="T">The type of the option value.</typeparam>
/// <param name="predicate">A function that evaluates whether the value contained in the option is valid or not.</param>
/// <param name="option">The input option.</param>
/// <returns>
/// Returns true if the <paramref name="option"/> <see cref="Option{T}.IsSome"/> and the <paramref name="predicate"/> return true when applied it.
/// Otherwise, returns false.
/// </returns>
public static bool Exists <T>(this Option <T> option, Func <T, bool> predicate)
=> OptionModule.Exists(predicate, option);
/// <summary>Applies the given function to <see cref="Option{T}"/> value when <see cref="Option{T}.IsSome"/>.</summary>
/// <typeparam name="T">The type of the option value.</typeparam>
/// <param name="action">The function to apply to value from the option.</param>
/// <param name="option">the input option.</param>
public static void Iterate <T>(this Option <T> option, Action <T> action)
=> OptionModule.Iterate(action, option);
/// <summary>
/// Evaluates a <see cref="Option{T}.Match{TResult}(Func{T, TResult}, Func{TResult})"/> that returns one when <see cref="Option{T}.IsSome"/>, otherwise returns 0
/// </summary>
/// <typeparam name="T">The type of the option value.</typeparam>
/// <param name="option">The input option.</param>
/// <returns>Returns one if the option <see cref="Option{T}.IsSome"/>, otherwise returns zero.</returns>
public static int Count <T>(this Option <T> option)
=> OptionModule.Count(option);
/// <summary>
/// Convert the <see cref="Option{T}"/> to an array of length 0 or 1.
/// </summary>
/// <typeparam name="T">The type of the option value.</typeparam>
/// <param name="option">the input option.</param>
/// <returns>Returns an array with a single element when <see cref="Option{T}.IsSome"/>. Otherwise returns an empty array.</returns>
public static T[] ToArray <T>(this Option <T> option)
=> OptionModule.ToArray(option);
/// <summary>
/// Convert the <see cref="Option{T}"/> to a list of length 0 or 1.
/// </summary>
/// <typeparam name="T">The type of the option value.</typeparam>
/// <param name="option">the input option.</param>
/// <returns>Returns a list with a single element when <see cref="Option{T}.IsSome"/>. Otherwise returns an empty list.</returns>
public static List <T> ToList <T>(this Option <T> option)
=> OptionModule.ToList(option);
/// <summary>
/// Convert the <see cref="Option{T}"/> to a <see cref="Nullable{T}"/> value.
/// </summary>
/// <typeparam name="T">The type of the option value.</typeparam>
/// <param name="option">The input option.</param>
/// <returns><see cref="Nullable{T}"/> value that contains the option value when <see cref="Option{T}.IsSome"/>. Otherwise returns a nullable with null value.</returns>
public static T?ToNullable <T>(this Option <T> option)
where T : struct
=> OptionModule.ToNullable(option);
/// <summary>
/// Convert the <see cref="Option{T}"/> to an <see cref="IEnumerable{T}"/> of length 0 or 1.
/// </summary>
/// <typeparam name="T">The type of the option value.</typeparam>
/// <param name="option">the input option.</param>
/// <returns>Returns an <see cref="IEnumerable{T}"/> with a single element when <see cref="Option{T}.IsSome"/>. Otherwise returns an <see cref="CollectionModule.Empty{T}"/>.</returns>
public static IEnumerable <T> AsEnumerable <T>(this Option <T> option)
=> OptionModule.AsEnumerable(option);
/// <summary>
/// Creates a new <typeparamref name="TState"/> value by applying the given <paramref name="folder"/> function
/// to <see cref="Option{T}.Some(T)"/> option value and <paramref name="state"/>.
/// Otherwise returns the <paramref name="state"/> itself.
/// </summary>
/// <typeparam name="T">The type of the option value.</typeparam>
/// <typeparam name="TState">The type of initial and final states</typeparam>
/// <param name="folder">The function to transform option value from the input option to a new state value.</param>
/// <param name="state">The initial state.</param>
/// <param name="option">The input option.</param>
/// <returns>
/// Returns a new <typeparamref name="TState"/> value by applying the given <paramref name="folder"/> function
/// to <see cref="Option{T}.Some(T)"/> option value and <paramref name="state"/>.
/// Otherwise returns the <paramref name="state"/> itself.
/// </returns>
public static TState FoldBack <T, TState>(this Option <T> option, Func <T, TState, TState> folder, TState state)
=> OptionModule.FoldBack(folder, option, state);
/// <summary>
/// Creates a new <typeparamref name="TState"/> value by applying the given <paramref name="folder"/> function
/// to <paramref name="state"/> and <see cref="Option{T}.Some(T)"/> option value.
/// Otherwise returns the <paramref name="state"/> itself.
/// </summary>
/// <typeparam name="T">The type of the option value.</typeparam>
/// <typeparam name="TState">The type of initial and final states</typeparam>
/// <param name="folder">The function to transform option value from the input option to a new state value.</param>
/// <param name="state">The initial state.</param>
/// <param name="option">The input option.</param>
/// <returns>
/// Returns a new <typeparamref name="TState"/> value by applying the given <paramref name="folder"/> function
/// to <paramref name="state"/> and <see cref="Option{T}.Some(T)"/> option value.
/// Otherwise returns the <paramref name="state"/> itself.
/// </returns>
public static TState Fold <T, TState>(this Option <T> option, TState state, Func <TState, T, TState> folder)
=> OptionModule.Fold(folder, state, option);
/// <summary>
/// Creates a new <see cref="Option{T}"/> whose value is the result of applying the given <paramref name="binder"/> function
/// to <paramref name="option"/> value.
/// </summary>
/// <typeparam name="T">The type of the option value.</typeparam>
/// <typeparam name="TResult">The type of the option value returned by <paramref name="binder"/> function.</typeparam>
/// <param name="binder">The function to transform option value from the input option to a new <see cref="Option{T}"/>.</param>
/// <param name="option">The input option.</param>
/// <returns>
/// Returns a new <see cref="Option{T}"/> whose value is the result of applying the given <paramref name="binder"/> function
/// to <paramref name="option"/> value.
/// </returns>
public static Option <TResult> Bind <T, TResult>(this Option <T> option, Func <T, Option <TResult> > binder)
=> OptionModule.Bind(binder, option);
/// <summary>
/// Creates a new <see cref="Option{T}"/> whose value is the result of applying the given <paramref name="applying"/> function
/// to <see cref="Option{T}.Some(T)"/> value when both <paramref name="applying"/> and <paramref name="option"/> are <see cref="Option{T}.IsSome"/>.
/// Otherwise returns an <see cref="Option{T}.None"/>.
/// </summary>
/// <typeparam name="T">The type of the option value.</typeparam>
/// <typeparam name="TResult">The type of the value returned by <paramref name="applying"/> function.</typeparam>
/// <param name="applying">The option function to transform option value from the input option.</param>
/// <param name="option">The input option.</param>
/// <returns>
/// Returns a new <see cref="Option{T}"/> whose value is the result of applying the given <paramref name="applying"/> function
/// to <see cref="Option{T}.Some(T)"/> value when both <paramref name="applying"/> and <paramref name="option"/> are <see cref="Option{T}.IsSome"/>.
/// Otherwise returns an <see cref="Option{T}.None"/>.
/// </returns>
public static Option <TResult> Apply <T, TResult>(this Option <T> option, Option <Func <T, TResult> > applying)
=> OptionModule.Apply(applying, option);
/// <summary>
/// Creates a new <see cref="Option{T}"/> whose value is the result of applying the given <paramref name="mapping"/> function
/// to <see cref="Option{T}.Some(T)"/> value. Otherwise returns an <see cref="Option{T}.None"/>.
/// </summary>
/// <typeparam name="T">The type of the option value.</typeparam>
/// <typeparam name="TResult">The type of the value returned by <paramref name="mapping"/> function.</typeparam>
/// <param name="mapping">The function to transform option value from the input option.</param>
/// <param name="option">The input option.</param>
/// <returns>
/// Returns a new <see cref="Option{T}"/> whose value is the result of applying the given <paramref name="mapping"/> function
/// is the <paramref name="option"/> <see cref="Option{T}.IsSome"/>. Otherwise returns an <see cref="Option{T}.None"/>.
/// </returns>
public static Option <TResult> Map <T, TResult>(this Option <T> option, Func <T, TResult> mapping)
=> OptionModule.Map(mapping, option);