Class OptionExtensions

Extension methods for the Option<T> type.

Inheritance

object

OptionExtensions

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Namespace: RustyOptions

Assembly: RustyOptions.dll

Syntax

public static class OptionExtensions

Methods

AndThen<T1, T2>(Option<T1>, Func<T1, Option<T2>>)

Returns None if the option is None, otherwise calls thenFn with the wrapped value and returns the result.

Declaration

public static Option<T2> AndThen<T1, T2>(this Option<T1> self, Func<T1, Option<T2>> thenFn) where T1 : notnull where T2 : notnull

Parameters

Type	Name	Description
Option<T1>	self	The first option.
Func<T1, Option<T2>>	thenFn	The function to call with the contained value, if there is a contained value.

Returns

Type	Description
Option<T2>

Type Parameters

Name	Description
T1	The type contained by the first option.
T2	The type contained by the second option.

Exceptions

Type	Condition
ArgumentNullException	Thrown if thenFn is null.

And<T1, T2>(Option<T1>, Option<T2>)

Returns None if self is None, otherwise returns other.

Declaration

public static Option<T2> And<T1, T2>(this Option<T1> self, Option<T2> other) where T1 : notnull where T2 : notnull

Parameters

Type	Name	Description
Option<T1>	self	The first option.
Option<T2>	other	The second option.

Returns

Type	Description
Option<T2>

Type Parameters

Name	Description
T1	The type contained by the first option.
T2	The type contained by the second option.

AsOption<T>(T?)

Wraps the given value in an Option<T>.

NOTE: Null values will be returned as None, while non-null values will be returned as Some.

Declaration

public static Option<T> AsOption<T>(this T? value) where T : struct

Parameters

Type	Name	Description
T?	value

Returns

Type	Description
Option<T>	The value wrapped in an Option<T>

Type Parameters

Name	Description
T

AsOption<T>(T?)

Wraps the given value in an Option<T>.

NOTE: Null values will be returned as None, while non-null values will be returned as Some.

Declaration

public static Option<T> AsOption<T>(this T? value) where T : class

Parameters

Type	Name	Description
T	value

Returns

Type	Description
Option<T>	The value wrapped in an Option<T>

Type Parameters

Name	Description
T

Expect<T>(Option<T>, string)

Returns the contained Some value, or throws an InvalidOperationException if the value is None.

Declaration

public static T Expect<T>(this Option<T> self, string message) where T : notnull

Parameters

Type	Name	Description
Option<T>	self	The option to unwrap.
string	message	The message for the exception that gets thrown if the option has no value.

Returns

Type	Description
T	The value contained in the option.

Type Parameters

Name	Description
T	The type of the option.

Exceptions

Type	Condition
InvalidOperationException	Thrown if the option does not contain a value.

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

Returns None if the option is None, otherwise calls predicate and returns Some if the predicated returns true, otherwise None.

Declaration

public static Option<T> Filter<T>(this Option<T> self, Func<T, bool> predicate) where T : notnull

Parameters

Type	Name	Description
Option<T>	self	The option to check.
Func<T, bool>	predicate	The function that determines if the value in the option is valid to return.

Returns

Type	Description
Option<T>	Some if the option is Some and the predicate returns true, otherwise None.

Type Parameters

Name	Description
T	The type of the value.

Exceptions

Type	Condition
ArgumentNullException	Thrown if predicate is null.

Flatten<T>(Option<Option<T>>)

Removes one level of nesting from nested options.

Declaration

public static Option<T> Flatten<T>(this Option<Option<T>> self) where T : notnull

Parameters

Type	Name	Description
Option<Option<T>>	self	The nested option to flatten.

Returns

Type	Description
Option<T>	The given option with one level of nesting removed.

Type Parameters

Name	Description
T	The type of the value.

MapOrElse<T1, T2>(Option<T1>, Func<T1, T2>, Func<T2>)

Computes a default function result (if None), or applies a different function to the contained value (if Some).

Declaration

public static T2 MapOrElse<T1, T2>(this Option<T1> self, Func<T1, T2> mapper, Func<T2> defaultFactory) where T1 : notnull where T2 : notnull

Parameters

Type	Name	Description
Option<T1>	self	The option to map.
Func<T1, T2>	mapper	The function that maps the value contained in the option.
Func<T2>	defaultFactory	The function that lazily generates a default value, if required.

Returns

Type	Description
T2	The mapped value, or the default value.

Type Parameters

Name	Description
T1	The type of the option's value.
T2	The return type after mapping.

Exceptions

Type	Condition
ArgumentNullException	Thrown if mapper or defaultFactory is null.

MapOr<T1, T2>(Option<T1>, Func<T1, T2>, T2)

Returns the provided default result (if None), or applies a function to the contained value (if Some).

Arguments passed to MapOr<T1, T2>(Option<T1>, Func<T1, T2>, T2) are eagerly evaluated; if you are passing the result of a function call, it is recommended to use MapOrElse<T1, T2>(Option<T1>, Func<T1, T2>, Func<T2>), which is lazily evaluated.

Declaration

public static T2 MapOr<T1, T2>(this Option<T1> self, Func<T1, T2> mapper, T2 defaultValue) where T1 : notnull where T2 : notnull

Parameters

Type	Name	Description
Option<T1>	self	The option to map.
Func<T1, T2>	mapper	The function that maps the value contained in the option.
T2	defaultValue	The default value to return if the option is None.

Returns

Type	Description
T2	The mapped value, or the default value.

Type Parameters

Name	Description
T1	The type of the option's value.
T2	The return type after mapping.

Exceptions

Type	Condition
ArgumentNullException	Thrown if mapper is null.

Map<T1, T2>(Option<T1>, Func<T1, T2>)

If the option has a value, passes that option to the mapper function and returns that value as a Some.

Declaration

public static Option<T2> Map<T1, T2>(this Option<T1> self, Func<T1, T2> mapper) where T1 : notnull where T2 : notnull

Parameters

Type	Name	Description
Option<T1>	self	The option to map.
Func<T1, T2>	mapper	The function that maps the value contained in the option.

Returns

Type	Description
Option<T2>	The mapped value as Some, or None.

Type Parameters

Name	Description
T1	The type of the option.
T2	The type returned by the mapper functions.

Exceptions

Type	Condition
ArgumentNullException	Thrown if mapper is null.

None<T>(T)

Returns None option typed to match value. The value is not used except to determine the type of the option.

Declaration

public static Option<T> None<T>(this T value) where T : notnull

Parameters

Type	Name	Description
T	value	The value used to determine the type of the returned None option. The value itself is not used.

Returns

Type	Description
Option<T>	A None option.

Type Parameters

Name	Description
T	The type used in the returned Option<T>.

OrElse<T>(Option<T>, Func<Option<T>>)

Returns self if it contains a value, otherwise calls elseFn and returns the result.

Declaration

public static Option<T> OrElse<T>(this Option<T> self, Func<Option<T>> elseFn) where T : notnull

Parameters

Type	Name	Description
Option<T>	self	The option.
Func<Option<T>>	elseFn	The function that creates the alternate value if the option is None.

Returns

Type	Description
Option<T>

Type Parameters

Name	Description
T	The type contained by the option.

Exceptions

Type	Condition
ArgumentNullException	Thrown if elseFn is null.

Or<T>(Option<T>, Option<T>)

Returns self if it contains a value, otherwise returns other.

Arguments passed to or are eagerly evaluated; if you are passing the result of a function call, it is recommended to use OrElse<T>(Option<T>, Func<Option<T>>), which is lazily evaluated.

Declaration

public static Option<T> Or<T>(this Option<T> self, Option<T> other) where T : notnull

Parameters

Type	Name	Description
Option<T>	self	The first option.
Option<T>	other	The replacement option to use if the first option is None.

Returns

Type	Description
Option<T>

Type Parameters

Name	Description
T	The type contained by the option.

Some<T>(T)

Wraps the given value in an Option<T>.

NOTE: Null values will be returned as None, while non-null values will be returned as Some.

Declaration

public static Option<T> Some<T>(this T value) where T : notnull

Parameters

Type	Name	Description
T	value	The value that will be contained in the Option.

Returns

Type	Description
Option<T>	The value wrapped in an Option<T>

Type Parameters

Name	Description
T	The type used in the returned Option<T>.

UnwrapOrElse<T>(Option<T>, Func<T>)

Returns the contained Some value or computes a default using the provided defaultFactory.

Declaration

public static T UnwrapOrElse<T>(this Option<T> self, Func<T> defaultFactory) where T : notnull

Parameters

Type	Name	Description
Option<T>	self	The option to unwrap.
Func<T>	defaultFactory	A function that returns a default value to use if the option is None.

Returns

Type	Description
T

Type Parameters

Name	Description
T	The type of the option.

Exceptions

Type	Condition
ArgumentNullException	Thrown if defaultFactory is null.

UnwrapOr<T>(Option<T>, T)

Returns the contained Some value or a provided default.

Declaration

public static T UnwrapOr<T>(this Option<T> self, T defaultValue) where T : notnull

Parameters

Type	Name	Description
Option<T>	self	The option to bind.
T	defaultValue	The default value to return if the option is None.

Returns

Type	Description
T

Type Parameters

Name	Description
T	The type of the option.

Xor<T>(Option<T>, Option<T>)

Returns Some if exactly one of self, other is Some, otherwise returns None.

Declaration

public static Option<T> Xor<T>(this Option<T> self, Option<T> other) where T : notnull

Parameters

Type	Name	Description
Option<T>	self	The option.
Option<T>	other	The other option.

Returns

Type	Description
Option<T>

Type Parameters

Name	Description
T	The type contained by the option.

ZipWith<T1, T2, T3>(Option<T1>, Option<T2>, Func<T1, T2, T3>)

Zips this Option and another Option with function zipper.

If this option is Some(s) and other is Some(o), this method returns Some(zipper(s, o)). Otherwise, None is returned.

Declaration

public static Option<T3> ZipWith<T1, T2, T3>(this Option<T1> self, Option<T2> other, Func<T1, T2, T3> zipper) where T1 : notnull where T2 : notnull where T3 : notnull

Parameters

Type	Name	Description
Option<T1>	self	The first option.
Option<T2>	other	The second option.
Func<T1, T2, T3>	zipper	A functon that combines values from the two options into a new type.

Returns

Type	Description
Option<T3>	An option contianing the result of passing both values to the zipper function, or None.

Type Parameters

Name	Description
T1	The type contained by the first option.
T2	The type contained by the second option.
T3	The type returned by the zipper function.

Exceptions

Type	Condition
ArgumentNullException	Thrown if zipper is null.

Zip<T1, T2>(Option<T1>, Option<T2>)

Zips this Option with another Option.

If this option is Some(s) and other is Some(o), this method returns Some((s, o)). Otherwise, None is returned.

Declaration

public static Option<(T1, T2)> Zip<T1, T2>(this Option<T1> self, Option<T2> other) where T1 : notnull where T2 : notnull

Parameters

Type	Name	Description
Option<T1>	self	The first option.
Option<T2>	other	The second option.

Returns

Type	Description
Option<(T1, T2)>	An option containing the values from both input options, if both have values. Otherwise, None.

Type Parameters

Name	Description
T1	The type contained by the first option.
T2	The type contained by the second option.