Class LinqToOpt

LINQ facilities for options.

Inheritance

Object

LinqToOpt

Inherited Members

Object.Equals(Object)

Object.Equals(Object, Object)

Object.GetHashCode()

Object.GetType()

Object.MemberwiseClone()

Object.ReferenceEquals(Object, Object)

Object.ToString()

Namespace: Hgk.Zero.Options.Linq

Assembly: Hgk.Zero.Options.dll

Syntax

public static class LinqToOpt

Remarks

This class contains a large number of LINQ-compatible methods. While all options are also enumerables, and can therefore be used with methods provided by Enumerable, most of the operators are specialized here for options in order to optimize the algorithms for use with zero- or one-element collections (such as Distinct<TSource>(IOpt<TSource>)), and also to return options from operations guaranteed to return at most one element when performed on an option (such as Zip<TFirst, TSecond, TResult>(IOpt<TFirst>, IEnumerable<TSecond>, Func<TFirst, TSecond, TResult>)). In general, the result of applying any LINQ operation in this class to an option is defined to be sequence-equal to the result of applying the same operation from Enumerable to the same option.

Similarly to the methods in Enumerable, most option-returning methods in this class are implemented using deferred execution; that is, the query represented by the method is not actually executed until the contents of the result are resolved directly, for example, by enumeration, using foreach, or calling a method such as ToFixed<TSource>(IOpt<TSource>) or Match<TSource, TResult>(IOpt<TSource>, Func<TResult>, Func<TSource, TResult>).

Some methods instead use or return Opt<T>, which is a type for fixed, immutable options. The contents of these are immediate and not deferred.

Methods

Aggregate<TSource>(IOpt<TSource>, Func<TSource, TSource, TSource>)

Applies an accumulator function over the elements of an option.

Declaration

public static TSource Aggregate<TSource>(this IOpt<TSource> source, Func<TSource, TSource, TSource> func)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TSource, TSource>	func	An accumulator function to be applied to an element of source.

Returns

Type	Description
TSource	The final accumulator value, which is the single element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

Since an option can only ever have zero elements or one element, func is never called (but must still be supplied).

Exceptions

Type	Condition
ArgumentNullException	source or func is null.
InvalidOperationException	source is empty.

Aggregate<TSource, TAccumulate>(IOpt<TSource>, TAccumulate, Func<TAccumulate, TSource, TAccumulate>)

Applies an accumulator function over the elements of an option, using the specified seed value.

Declaration

public static TAccumulate Aggregate<TSource, TAccumulate>(this IOpt<TSource> source, TAccumulate seed, Func<TAccumulate, TSource, TAccumulate> func)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
TAccumulate	seed	The initial value for the accumulator.
Func<TAccumulate, TSource, TAccumulate>	func	An accumulator function to be applied to the accumulator and an element of source.

Returns

Type	Description
TAccumulate	The final accumulator value, which is either seed, if source is empty, or the result of applying func to seed and the single element of source, otherwise.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TAccumulate	The type of the accumulator value.

Exceptions

Type	Condition
ArgumentNullException	source or func is null.

Aggregate<TSource, TAccumulate, TResult>(IOpt<TSource>, TAccumulate, Func<TAccumulate, TSource, TAccumulate>, Func<TAccumulate, TResult>)

Applies an accumulator function over the elements of an option, using the specified seed value, and transforming the final result with the specified result selector.

Declaration

public static TResult Aggregate<TSource, TAccumulate, TResult>(this IOpt<TSource> source, TAccumulate seed, Func<TAccumulate, TSource, TAccumulate> func, Func<TAccumulate, TResult> resultSelector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
TAccumulate	seed	The initial value for the accumulator.
Func<TAccumulate, TSource, TAccumulate>	func	An accumulator function to be applied to the accumulator and an element of source.
Func<TAccumulate, TResult>	resultSelector	A function to transform the accumulator value into the result.

Returns

Type	Description
TResult	The result of applying resultSelector to the final accumulator value, which is either seed, if source is empty, or the result of applying func to seed and the single element of source, otherwise.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TAccumulate	The type of the accumulator value.
TResult	The type of the result.

Exceptions

Type	Condition
ArgumentNullException	source, func, or resultSelector is null.

All<TSource>(IOpt<TSource>, Func<TSource, Boolean>)

Returns whether all elements of an option satisfy a predicate.

Declaration

public static bool All<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.

Returns

Type	Description
Boolean	true, if source is empty or contains an element that satisfies predicate; otherwise, false.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

Any<TSource>(IOpt<TSource>)

Returns whether an option contains any elements.

Declaration

public static bool Any<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.

Returns

Type	Description
Boolean	true if source contains an element; otherwise, false.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Any<TSource>(IOpt<TSource>, Func<TSource, Boolean>)

Returns whether any element of an option satisfies a predicate.

Declaration

public static bool Any<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.

Returns

Type	Description
Boolean	true, if source contains an element that satisfies predicate; otherwise, false.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

AsIOpt<TSource>(IOpt<TSource>)

Returns this option typed as IOpt<T>.

Declaration

public static IOpt<TSource> AsIOpt<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to type as IOpt<T>.

Returns

Type	Description
IOpt<TSource>	source, typed as IOpt<T>.

Type Parameters

Name	Description
TSource	The element type of source.

Average(IOpt<Decimal>)

Computes the average of the contents of an option.

Declaration

public static decimal Average(this IOpt<decimal> source)

Parameters

Type	Name	Description
IOpt<Decimal>	source	A source option.

Returns

Type	Description
Decimal	The value of the only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Average(IOpt<Double>)

Computes the average of the contents of an option.

Declaration

public static double Average(this IOpt<double> source)

Parameters

Type	Name	Description
IOpt<Double>	source	A source option.

Returns

Type	Description
Double	The value of the only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Average(IOpt<Int32>)

Computes the average of the contents of an option.

Declaration

public static double Average(this IOpt<int> source)

Parameters

Type	Name	Description
IOpt<Int32>	source	A source option.

Returns

Type	Description
Double	The value of the only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Average(IOpt<Int64>)

Computes the average of the contents of an option.

Declaration

public static double Average(this IOpt<long> source)

Parameters

Type	Name	Description
IOpt<Int64>	source	A source option.

Returns

Type	Description
Double	The value of the only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Average(IOpt<Nullable<Decimal>>)

Computes the average of the non-null contents of an option.

Declaration

public static decimal? Average(this IOpt<decimal? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Decimal>>	source	A source option.

Returns

Type	Description
Nullable<Decimal>	The value of the only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Average(IOpt<Nullable<Double>>)

Computes the average of the non-null contents of an option.

Declaration

public static double? Average(this IOpt<double? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Double>>	source	A source option.

Returns

Type	Description
Nullable<Double>	The value of the only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Average(IOpt<Nullable<Int32>>)

Computes the average of the non-null contents of an option.

Declaration

public static double? Average(this IOpt<int? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Int32>>	source	A source option.

Returns

Type	Description
Nullable<Double>	The value of the only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Average(IOpt<Nullable<Int64>>)

Computes the average of the non-null contents of an option.

Declaration

public static double? Average(this IOpt<long? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Int64>>	source	A source option.

Returns

Type	Description
Nullable<Double>	The value of the only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Average(IOpt<Nullable<Single>>)

Computes the average of the non-null contents of an option.

Declaration

public static float? Average(this IOpt<float? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Single>>	source	A source option.

Returns

Type	Description
Nullable<Single>	The value of the only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Average(IOpt<Single>)

Computes the average of the contents of an option.

Declaration

public static float Average(this IOpt<float> source)

Parameters

Type	Name	Description
IOpt<Single>	source	A source option.

Returns

Type	Description
Single	The value of the only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Average<TSource>(IOpt<TSource>, Func<TSource, Decimal>)

Computes the average of a projection of the contents of an option.

Declaration

public static decimal Average<TSource>(this IOpt<TSource> source, Func<TSource, decimal> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Decimal>	selector	A transform function applied to each element of source.

Returns

Type	Description
Decimal	The value of the result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Average<TSource>(IOpt<TSource>, Func<TSource, Double>)

Computes the average of a projection of the contents of an option.

Declaration

public static double Average<TSource>(this IOpt<TSource> source, Func<TSource, double> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Double>	selector	A transform function applied to each element of source.

Returns

Type	Description
Double	The value of the result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Average<TSource>(IOpt<TSource>, Func<TSource, Int32>)

Computes the average of a projection of the contents of an option.

Declaration

public static double Average<TSource>(this IOpt<TSource> source, Func<TSource, int> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Int32>	selector	A transform function applied to each element of source.

Returns

Type	Description
Double	The value of the result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Average<TSource>(IOpt<TSource>, Func<TSource, Int64>)

Computes the average of a projection of the contents of an option.

Declaration

public static double Average<TSource>(this IOpt<TSource> source, Func<TSource, long> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Int64>	selector	A transform function applied to each element of source.

Returns

Type	Description
Double	The value of the result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Average<TSource>(IOpt<TSource>, Func<TSource, Nullable<Decimal>>)

Computes the average of the non-null elements of a projection of the contents of an option.

Declaration

public static decimal? Average<TSource>(this IOpt<TSource> source, Func<TSource, decimal? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Decimal>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Decimal>	The value of the result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Average<TSource>(IOpt<TSource>, Func<TSource, Nullable<Double>>)

Computes the average of the non-null elements of a projection of the contents of an option.

Declaration

public static double? Average<TSource>(this IOpt<TSource> source, Func<TSource, double? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Double>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Double>	The value of the result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Average<TSource>(IOpt<TSource>, Func<TSource, Nullable<Int32>>)

Computes the average of the non-null elements of a projection of the contents of an option.

Declaration

public static double? Average<TSource>(this IOpt<TSource> source, Func<TSource, int? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Int32>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Double>	The value of the result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Average<TSource>(IOpt<TSource>, Func<TSource, Nullable<Int64>>)

Computes the average of the non-null elements of a projection of the contents of an option.

Declaration

public static double? Average<TSource>(this IOpt<TSource> source, Func<TSource, long? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Int64>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Double>	The value of the result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Average<TSource>(IOpt<TSource>, Func<TSource, Nullable<Single>>)

Computes the average of the non-null elements of a projection of the contents of an option.

Declaration

public static float? Average<TSource>(this IOpt<TSource> source, Func<TSource, float? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Single>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Single>	The value of the result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Average<TSource>(IOpt<TSource>, Func<TSource, Single>)

Computes the average of a projection of the contents of an option.

Declaration

public static float Average<TSource>(this IOpt<TSource> source, Func<TSource, float> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Single>	selector	A transform function applied to each element of source.

Returns

Type	Description
Single	The value of the result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Cast<TResult>(IOpt)

Casts the elements of an option to the specified type.

Declaration

public static IOpt<TResult> Cast<TResult>(this IOpt source)

Parameters

Type	Name	Description
IOpt	source	A source option.

Returns

Type	Description
IOpt<TResult>	An option having the same contents as source, cast to TResult.

Type Parameters

Name	Description
TResult	The type to which to cast the elements of source.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

If source is already an IOpt<T> with TResult as its element type, it is returned unchanged.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidCastException	source is not empty and its element cannot be cast to TResult. (Deferred.)

Contains<TSource>(IOpt<TSource>, TSource)

Determines whether an option contains an element that equals the specified value.

Declaration

public static bool Contains<TSource>(this IOpt<TSource> source, TSource value)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
TSource	value	A value to find in source.

Returns

Type	Description
Boolean	true, if source contains an element that equals value; otherwise, false.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

The comparison, if any, is performed using Default for TSource.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Contains<TSource>(IOpt<TSource>, TSource, IEqualityComparer<TSource>)

Determines whether an option contains an element that equals the specified value, according to the specified comparer.

Declaration

public static bool Contains<TSource>(this IOpt<TSource> source, TSource value, IEqualityComparer<TSource> comparer)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
TSource	value	A value to find in source.
IEqualityComparer<TSource>	comparer	A comparer to determine whether values are equal. (If null, Default is used.)

Returns

Type	Description
Boolean	true, if source contains an element that equals value; otherwise, false.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

The comparison, if any, is performed using comparer. If comparer is null, Default for TSource is used instead.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Count<TSource>(IOpt<TSource>)

Returns the number of elements in an option.

Declaration

public static int Count<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.

Returns

Type	Description
Int32	1 if source contains an element; otherwise, 0.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Count<TSource>(IOpt<TSource>, Func<TSource, Boolean>)

Returns the number of elements of an option that satisfy a predicate.

Declaration

public static int Count<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.

Returns

Type	Description
Int32	1, if source contains an element that satisfies predicate; otherwise, 0.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

DefaultIfEmpty<TSource>(IOpt<TSource>)

Returns a full option containing either the same contents as a specified option, if it is full, or the default value for the type, if it is empty.

Declaration

public static IOpt<TSource> DefaultIfEmpty<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.

Returns

Type	Description
IOpt<TSource>	An option that is equivalent to source, if source is full; otherwise, a full option containing the langword_csharp_default value for the type.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source is null.

DefaultIfEmpty<TSource>(IOpt<TSource>, TSource)

Returns a full option containing either the same contents as a specified option, if it is full, or a specified default value, if it is empty.

Declaration

public static IOpt<TSource> DefaultIfEmpty<TSource>(this IOpt<TSource> source, TSource defaultValue)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
TSource	defaultValue	A default value for the result to contain if source is empty.

Returns

Type	Description
IOpt<TSource>	An option that is equivalent to source, if source is full; otherwise, a full option containing defaultValue.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Distinct<TSource>(IOpt<TSource>)

Returns distinct elements from an option.

Declaration

public static IOpt<TSource> Distinct<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.

Returns

Type	Description
IOpt<TSource>	source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

Since an option, by virtue of being a zero- or one-element sequence, never contains duplicate elements, this method returns source unmodified (after ensuring that it is not null).

Exceptions

Type	Condition
ArgumentNullException	source is null.

Distinct<TSource>(IOpt<TSource>, IEqualityComparer<TSource>)

Returns distinct elements from an option.

Declaration

public static IOpt<TSource> Distinct<TSource>(this IOpt<TSource> source, IEqualityComparer<TSource> comparer)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
IEqualityComparer<TSource>	comparer	A comparer used to test values for equality. (This parameter is ignored.)

Returns

Type	Description
IOpt<TSource>	source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

Since an option, by virtue of being a zero- or one-element sequence, never contains duplicate elements, this method returns source unmodified (after ensuring that it is not null).

Exceptions

Type	Condition
ArgumentNullException	source is null.

ElementAt<TSource>(IOpt<TSource>, Int32)

Returns the element at a specified index in an option.

Declaration

public static TSource ElementAt<TSource>(this IOpt<TSource> source, int index)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
Int32	index	The index of the element to retrieve.

Returns

Type	Description
TSource	The element at the specified position in source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
ArgumentOutOfRangeException	source is empty or index is nonzero.

ElementAtOrDefault<TSource>(IOpt<TSource>, Int32)

Returns the element at a specified index in an option or the type's default value if the index is out of range.

Declaration

public static TSource ElementAtOrDefault<TSource>(this IOpt<TSource> source, int index)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
Int32	index	The index of the element to retrieve.

Returns

Type	Description
TSource	The default value of TSource if the index is outside the bounds of source; otherwise, the element at the specified position in source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

ElementAtOrDefault<TSource>(IOpt<TSource>, Int32, TSource)

Returns the element at a specified index in an option or a default value if the index is out of range.

Declaration

public static TSource ElementAtOrDefault<TSource>(this IOpt<TSource> source, int index, TSource defaultValue)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
Int32	index	The index of the element to retrieve.
TSource	defaultValue	A default value to return if index is out of bounds.

Returns

Type	Description
TSource	defaultValue if the index is outside the bounds of source; otherwise, the element at the specified position in source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Except<TSource>(IOpt<TSource>, IEnumerable<TSource>)

Finds the elements of an option that do not appear in a sequence.

Declaration

public static IOpt<TSource> Except<TSource>(this IOpt<TSource> first, IEnumerable<TSource> second)

Parameters

Type	Name	Description
IOpt<TSource>	first	An option whose elements are to be subtracted from.
IEnumerable<TSource>	second	A sequence of elements to subtract from first.

Returns

Type	Description
IOpt<TSource>	An option equivalent to first, if the element of first does not appear in second; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of first and second.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	first or second is null.

Except<TSource>(IOpt<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)

Finds the elements of an option that do not appear in a sequence, using the specified comparer to determine equality.

Declaration

public static IOpt<TSource> Except<TSource>(this IOpt<TSource> first, IEnumerable<TSource> second, IEqualityComparer<TSource> comparer)

Parameters

Type	Name	Description
IOpt<TSource>	first	An option whose elements are to be subtracted from.
IEnumerable<TSource>	second	A sequence of elements to subtract from first.
IEqualityComparer<TSource>	comparer	A comparer to determine whether elements are equal. (If null, Default is used.)

Returns

Type	Description
IOpt<TSource>	An option equivalent to first, if the element of first does not appear in second; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of first and second.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	first or second is null.

First<TSource>(IOpt<TSource>)

Returns the first element of an option.

Declaration

public static TSource First<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.

Returns

Type	Description
TSource	The first element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

First<TSource>(IOpt<TSource>, Func<TSource, Boolean>)

Returns the first element of an option that satisfies a condition.

Declaration

public static TSource First<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.

Returns

Type	Description
TSource	The first element of source that satisfies predicate.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source does not contain any element that satisfies predicate.

FirstOrDefault<TSource>(IOpt<TSource>)

Returns the first element of an option, or the default value for the type if the option is empty.

Declaration

public static TSource FirstOrDefault<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.

Returns

Type	Description
TSource	The first element of source, or the default value for TSource if source is empty.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

FirstOrDefault<TSource>(IOpt<TSource>, TSource)

Returns the first element of an option, or a specified default value if the option is empty.

Declaration

public static TSource FirstOrDefault<TSource>(this IOpt<TSource> source, TSource defaultValue)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
TSource	defaultValue	A default value to return if source contains no elements.

Returns

Type	Description
TSource	The first element of source, or defaultValue if source is empty.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

FirstOrDefault<TSource>(IOpt<TSource>, Func<TSource, Boolean>)

Returns the first element of an option that satisfies a condition, or the default value for the type if no such element is found.

Declaration

public static TSource FirstOrDefault<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.

Returns

Type	Description
TSource	The first element of source that satisfies predicate, or the default value for TSource if no such element is found.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

FirstOrDefault<TSource>(IOpt<TSource>, Func<TSource, Boolean>, TSource)

Returns the first element of an option that satisfies a condition, or a specified default value if no such element is found.

Declaration

public static TSource FirstOrDefault<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate, TSource defaultValue)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.
TSource	defaultValue	A default value to return if source contains no elements that satisfy predicate.

Returns

Type	Description
TSource	The first element of source that satisfies predicate, or defaultValue if no such element is found.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

Flatten<TSource>(IOpt<IOpt<TSource>>)

Collapses an option containing another option into a single option.

Declaration

public static IOpt<TSource> Flatten<TSource>(this IOpt<IOpt<TSource>> source)

Parameters

Type	Name	Description
IOpt<IOpt<TSource>>	source	An outer option containing an inner option.

Returns

Type	Description
IOpt<TSource>	An option equivalent to the inner option, if it exists; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The element type of the inner option.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source is null (immediate) or the element of source is null (deferred).

Flatten<TSource>(IOpt<Opt<TSource>>)

Collapses an option containing another option into a single option.

Declaration

public static IOpt<TSource> Flatten<TSource>(this IOpt<Opt<TSource>> source)

Parameters

Type	Name	Description
IOpt<Opt<TSource>>	source	An outer option containing an inner option.

Returns

Type	Description
IOpt<TSource>	An option equivalent to the inner option, if it exists; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The element type of the inner option.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source is null.

GroupBy<TSource, TKey>(IOpt<TSource>, Func<TSource, TKey>)

Groups the elements of an option by a selected key.

Declaration

public static IOpt<IOptGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IOpt<TSource> source, Func<TSource, TKey> keySelector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element.

Returns

Type	Description
IOpt<IOptGrouping<TKey, TSource>>	An option that contains a grouping for the element of source, if source is full; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to group elements.

Exceptions

Type	Condition
ArgumentNullException	source or keySelector is null.

GroupBy<TSource, TKey>(IOpt<TSource>, Func<TSource, TKey>, IEqualityComparer<TKey>)

Groups the elements of an option by a selected key.

Declaration

public static IOpt<IOptGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IOpt<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element.
IEqualityComparer<TKey>	comparer	A comparer to determine whether keys are equal. (This parameter is ignored.)

Returns

Type	Description
IOpt<IOptGrouping<TKey, TSource>>	An option that contains a grouping for the element of source, if source is full; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to group elements.

Exceptions

Type	Condition
ArgumentNullException	source or keySelector is null.

GroupBy<TSource, TKey, TElement>(IOpt<TSource>, Func<TSource, TKey>, Func<TSource, TElement>)

Groups the projected elements of an option by a selected key.

Declaration

public static IOpt<IOptGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IOpt<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element of source.
Func<TSource, TElement>	elementSelector	A function to transform an element of source to an element to include in a grouping.

Returns

Type	Description
IOpt<IOptGrouping<TKey, TElement>>	An option that contains a grouping for the projected element of source, if source is full; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to group elements.
TElement	The type of the transformed elements to include in the grouping.

Exceptions

Type	Condition
ArgumentNullException	source, keySelector, or elementSelector is null.

GroupBy<TSource, TKey, TElement>(IOpt<TSource>, Func<TSource, TKey>, Func<TSource, TElement>, IEqualityComparer<TKey>)

Groups the projected elements of an option by a selected key.

Declaration

public static IOpt<IOptGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IOpt<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey> comparer)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element of source.
Func<TSource, TElement>	elementSelector	A function to transform an element of source to an element to include in a grouping.
IEqualityComparer<TKey>	comparer	A comparer to determine whether keys are equal. (This parameter is ignored.)

Returns

Type	Description
IOpt<IOptGrouping<TKey, TElement>>	An option that contains a grouping for the projected element of source, if source is full; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to group elements.
TElement	The type of the transformed elements to include in the grouping.

Exceptions

Type	Condition
ArgumentNullException	source, keySelector, or elementSelector is null.

GroupBy<TSource, TKey, TResult>(IOpt<TSource>, Func<TSource, TKey>, Func<TKey, IOpt<TSource>, TResult>)

Groups the elements of an option by a selected key, then applies a transform to each grouping.

Declaration

public static IOpt<TResult> GroupBy<TSource, TKey, TResult>(this IOpt<TSource> source, Func<TSource, TKey> keySelector, Func<TKey, IOpt<TSource>, TResult> resultSelector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element of source.
Func<TKey, IOpt<TSource>, TResult>	resultSelector	A function to select a result value for each grouping.

Returns

Type	Description
IOpt<TResult>	An option that contains the result of applying resultSelector to the grouping for the element of source, if source is full; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to group elements.
TResult	The type of the result value for each grouping.

Exceptions

Type	Condition
ArgumentNullException	source, keySelector, or resultSelector is null.

GroupBy<TSource, TKey, TResult>(IOpt<TSource>, Func<TSource, TKey>, Func<TKey, IOpt<TSource>, TResult>, IEqualityComparer<TKey>)

Groups the elements of an option by a selected key, then applies a transform to each grouping.

Declaration

public static IOpt<TResult> GroupBy<TSource, TKey, TResult>(this IOpt<TSource> source, Func<TSource, TKey> keySelector, Func<TKey, IOpt<TSource>, TResult> resultSelector, IEqualityComparer<TKey> comparer)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element of source.
Func<TKey, IOpt<TSource>, TResult>	resultSelector	A function to select a result value for each grouping.
IEqualityComparer<TKey>	comparer	A comparer to determine whether keys are equal. (This parameter is ignored.)

Returns

Type	Description
IOpt<TResult>	An option that contains the result of applying resultSelector to the grouping for the element of source, if source is full; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to group elements.
TResult	The type of the result value for each grouping.

Exceptions

Type	Condition
ArgumentNullException	source, keySelector, or resultSelector is null.

GroupBy<TSource, TKey, TElement, TResult>(IOpt<TSource>, Func<TSource, TKey>, Func<TSource, TElement>, Func<TKey, IOpt<TElement>, TResult>)

Groups the projected elements of an option by a selected key, then applies a transform to each grouping.

Declaration

public static IOpt<TResult> GroupBy<TSource, TKey, TElement, TResult>(this IOpt<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, Func<TKey, IOpt<TElement>, TResult> resultSelector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element of source.
Func<TSource, TElement>	elementSelector	A function to transform an element of source to an element to include in a grouping.
Func<TKey, IOpt<TElement>, TResult>	resultSelector	A function to select a result value for each grouping.

Returns

Type	Description
IOpt<TResult>	An option that contains the result of applying resultSelector to the grouping for the projected element of source, if source is full; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to group elements.
TElement	The type of the transformed elements to include in the grouping.
TResult	The type of the result value for each grouping.

Exceptions

Type	Condition
ArgumentNullException	source, keySelector, elementSelector, or resultSelector is null.

GroupBy<TSource, TKey, TElement, TResult>(IOpt<TSource>, Func<TSource, TKey>, Func<TSource, TElement>, Func<TKey, IOpt<TElement>, TResult>, IEqualityComparer<TKey>)

Groups the projected elements of an option by a selected key, then applies a transform to each grouping.

Declaration

public static IOpt<TResult> GroupBy<TSource, TKey, TElement, TResult>(this IOpt<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, Func<TKey, IOpt<TElement>, TResult> resultSelector, IEqualityComparer<TKey> comparer)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element of source.
Func<TSource, TElement>	elementSelector	A function to transform an element of source to an element to include in a grouping.
Func<TKey, IOpt<TElement>, TResult>	resultSelector	A function to select a result value for each grouping.
IEqualityComparer<TKey>	comparer	A comparer to determine whether keys are equal. (This parameter is ignored.)

Returns

Type	Description
IOpt<TResult>	An option that contains the result of applying resultSelector to the grouping for the projected element of source, if source is full; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to group elements.
TElement	The type of the transformed elements to include in the grouping.
TResult	The type of the result value for each grouping.

Exceptions

Type	Condition
ArgumentNullException	source, keySelector, elementSelector, or resultSelector is null.

GroupJoin<TOuter, TInner, TKey, TResult>(IOpt<TOuter>, IOpt<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, IOpt<TInner>, TResult>)

Joins each element of an outer option to a grouping of inner elements with matching keys, then applies a transform to each grouping.

Declaration

public static IOpt<TResult> GroupJoin<TOuter, TInner, TKey, TResult>(this IOpt<TOuter> outer, IOpt<TInner> inner, Func<TOuter, TKey> outerKeySelector, Func<TInner, TKey> innerKeySelector, Func<TOuter, IOpt<TInner>, TResult> resultSelector)

Parameters

Type	Name	Description
IOpt<TOuter>	outer	The outer option to join.
IOpt<TInner>	inner	The inner option to join.
Func<TOuter, TKey>	outerKeySelector	A function to select the key that corresponds to an element of outer.
Func<TInner, TKey>	innerKeySelector	A function to select the key that corresponds to an element of inner.
Func<TOuter, IOpt<TInner>, TResult>	resultSelector	A function to select a result value for each grouping.

Returns

Type	Description
IOpt<TResult>	An option that contains the result of applying resultSelector to the grouping for the element of outer and its corresponding elements of inner, if outer is full; otherwise, an empty option.

Type Parameters

Name	Description
TOuter	The type of the elements of outer.
TInner	The type of the elements of inner.
TKey	The type of the key used to match and group elements.
TResult	The type of the result value for each grouping.

Exceptions

Type	Condition
ArgumentNullException	outer, inner, outerKeySelector, innerKeySelector, or resultSelector is null.

GroupJoin<TOuter, TInner, TKey, TResult>(IOpt<TOuter>, IOpt<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, IOpt<TInner>, TResult>, IEqualityComparer<TKey>)

Joins each element of an outer option to a grouping of inner elements with matching keys, then applies a transform to each grouping.

Declaration

public static IOpt<TResult> GroupJoin<TOuter, TInner, TKey, TResult>(this IOpt<TOuter> outer, IOpt<TInner> inner, Func<TOuter, TKey> outerKeySelector, Func<TInner, TKey> innerKeySelector, Func<TOuter, IOpt<TInner>, TResult> resultSelector, IEqualityComparer<TKey> comparer)

Parameters

Type	Name	Description
IOpt<TOuter>	outer	The outer option to join.
IOpt<TInner>	inner	The inner option to join.
Func<TOuter, TKey>	outerKeySelector	A function to select the key that corresponds to an element of outer.
Func<TInner, TKey>	innerKeySelector	A function to select the key that corresponds to an element of inner.
Func<TOuter, IOpt<TInner>, TResult>	resultSelector	A function to select a result value for each grouping.
IEqualityComparer<TKey>	comparer	A comparer to determine whether keys are equal. (If null, Default is used.)

Returns

Type	Description
IOpt<TResult>	An option that contains the result of applying resultSelector to the grouping for the element of outer and its corresponding elements of inner, if outer is full; otherwise, an empty option.

Type Parameters

Name	Description
TOuter	The type of the elements of outer.
TInner	The type of the elements of inner.
TKey	The type of the key used to match and group elements.
TResult	The type of the result value for each grouping.

Exceptions

Type	Condition
ArgumentNullException	outer, inner, outerKeySelector, innerKeySelector, or resultSelector is null.

GroupJoin<TOuter, TInner, TKey, TResult>(IOpt<TOuter>, IEnumerable<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, IEnumerable<TInner>, TResult>)

Joins each element of an outer option to a grouping of inner elements with matching keys, then applies a transform to each grouping.

Declaration

public static IOpt<TResult> GroupJoin<TOuter, TInner, TKey, TResult>(this IOpt<TOuter> outer, IEnumerable<TInner> inner, Func<TOuter, TKey> outerKeySelector, Func<TInner, TKey> innerKeySelector, Func<TOuter, IEnumerable<TInner>, TResult> resultSelector)

Parameters

Type	Name	Description
IOpt<TOuter>	outer	The outer option to join.
IEnumerable<TInner>	inner	The inner sequence to join.
Func<TOuter, TKey>	outerKeySelector	A function to select the key that corresponds to an element of outer.
Func<TInner, TKey>	innerKeySelector	A function to select the key that corresponds to an element of inner.
Func<TOuter, IEnumerable<TInner>, TResult>	resultSelector	A function to select a result value for each grouping.

Returns

Type	Description
IOpt<TResult>	An option that contains the result of applying resultSelector to the grouping for the element of outer and its corresponding elements of inner, if outer is full; otherwise, an empty option.

Type Parameters

Name	Description
TOuter	The type of the elements of outer.
TInner	The type of the elements of inner.
TKey	The type of the key used to match and group elements.
TResult	The type of the result value for each grouping.

Exceptions

Type	Condition
ArgumentNullException	outer, inner, outerKeySelector, innerKeySelector, or resultSelector is null.

GroupJoin<TOuter, TInner, TKey, TResult>(IOpt<TOuter>, IEnumerable<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, IEnumerable<TInner>, TResult>, IEqualityComparer<TKey>)

Joins each element of an outer option to a grouping of inner elements with matching keys, then applies a transform to each grouping.

Declaration

public static IOpt<TResult> GroupJoin<TOuter, TInner, TKey, TResult>(this IOpt<TOuter> outer, IEnumerable<TInner> inner, Func<TOuter, TKey> outerKeySelector, Func<TInner, TKey> innerKeySelector, Func<TOuter, IEnumerable<TInner>, TResult> resultSelector, IEqualityComparer<TKey> comparer)

Parameters

Type	Name	Description
IOpt<TOuter>	outer	The outer option to join.
IEnumerable<TInner>	inner	The inner sequence to join.
Func<TOuter, TKey>	outerKeySelector	A function to select the key that corresponds to an element of outer.
Func<TInner, TKey>	innerKeySelector	A function to select the key that corresponds to an element of inner.
Func<TOuter, IEnumerable<TInner>, TResult>	resultSelector	A function to select a result value for each grouping.
IEqualityComparer<TKey>	comparer	A comparer to determine whether keys are equal. (If null, Default is used.)

Returns

Type	Description
IOpt<TResult>	An option that contains the result of applying resultSelector to the grouping for the element of outer and its corresponding elements of inner, if outer is full; otherwise, an empty option.

Type Parameters

Name	Description
TOuter	The type of the elements of outer.
TInner	The type of the elements of inner.
TKey	The type of the key used to match and group elements.
TResult	The type of the result value for each grouping.

Exceptions

Type	Condition
ArgumentNullException	outer, inner, outerKeySelector, innerKeySelector, or resultSelector is null.

Intersect<TSource>(IOpt<TSource>, IEnumerable<TSource>)

Finds the elements of an option that also appear in a sequence.

Declaration

public static IOpt<TSource> Intersect<TSource>(this IOpt<TSource> first, IEnumerable<TSource> second)

Parameters

Type	Name	Description
IOpt<TSource>	first	An option whose elements are to be compared.
IEnumerable<TSource>	second	A sequence of elements to be compared.

Returns

Type	Description
IOpt<TSource>	An option equivalent to first, if the element of first appears in second; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of first and second.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	first or second is null.

Intersect<TSource>(IOpt<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)

Finds the elements of an option that also appear in a sequence, using the specified comparer to determine equality.

Declaration

public static IOpt<TSource> Intersect<TSource>(this IOpt<TSource> first, IEnumerable<TSource> second, IEqualityComparer<TSource> comparer)

Parameters

Type	Name	Description
IOpt<TSource>	first	An option whose elements are to be compared.
IEnumerable<TSource>	second	A sequence of elements to be compared.
IEqualityComparer<TSource>	comparer	A comparer to determine whether elements are equal. (If null, Default is used.)

Returns

Type	Description
IOpt<TSource>	An option equivalent to first, if the element of first appears in second; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of first and second.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	first or second is null.

Join<TOuter, TInner, TKey, TResult>(IOpt<TOuter>, IOpt<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, TInner, TResult>)

Joins elements of an outer option with elements of an inner option having matching keys.

Declaration

public static IOpt<TResult> Join<TOuter, TInner, TKey, TResult>(this IOpt<TOuter> outer, IOpt<TInner> inner, Func<TOuter, TKey> outerKeySelector, Func<TInner, TKey> innerKeySelector, Func<TOuter, TInner, TResult> resultSelector)

Parameters

Type	Name	Description
IOpt<TOuter>	outer	The outer option to join.
IOpt<TInner>	inner	The inner option to join.
Func<TOuter, TKey>	outerKeySelector	A function to select the key that corresponds to an element of outer.
Func<TInner, TKey>	innerKeySelector	A function to select the key that corresponds to an element of inner.
Func<TOuter, TInner, TResult>	resultSelector	A function to select a result value for each matched pair.

Returns

Type	Description
IOpt<TResult>	An option that contains the result of applying resultSelector to the element of outer and the element of inner, if both options are full and their corresponding keys are equal; otherwise, an empty option.

Type Parameters

Name	Description
TOuter	The type of the elements of outer.
TInner	The type of the elements of inner.
TKey	The type of the key used to match elements.
TResult	The type of the result value for each matched pair.

Exceptions

Type	Condition
ArgumentNullException	outer, inner, outerKeySelector, innerKeySelector, or resultSelector is null.

Join<TOuter, TInner, TKey, TResult>(IOpt<TOuter>, IOpt<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, TInner, TResult>, IEqualityComparer<TKey>)

Joins elements of an outer option with elements of an inner option having matching keys.

Declaration

public static IOpt<TResult> Join<TOuter, TInner, TKey, TResult>(this IOpt<TOuter> outer, IOpt<TInner> inner, Func<TOuter, TKey> outerKeySelector, Func<TInner, TKey> innerKeySelector, Func<TOuter, TInner, TResult> resultSelector, IEqualityComparer<TKey> comparer)

Parameters

Type	Name	Description
IOpt<TOuter>	outer	The outer option to join.
IOpt<TInner>	inner	The inner option to join.
Func<TOuter, TKey>	outerKeySelector	A function to select the key that corresponds to an element of outer.
Func<TInner, TKey>	innerKeySelector	A function to select the key that corresponds to an element of inner.
Func<TOuter, TInner, TResult>	resultSelector	A function to select a result value for each matched pair.
IEqualityComparer<TKey>	comparer	A comparer to determine whether keys are equal. (If null, Default is used.)

Returns

Type	Description
IOpt<TResult>	An option that contains the result of applying resultSelector to the element of outer and the element of inner, if both options are full and their corresponding keys are equal according to comparer; otherwise, an empty option.

Type Parameters

Name	Description
TOuter	The type of the elements of outer.
TInner	The type of the elements of inner.
TKey	The type of the key used to match elements.
TResult	The type of the result value for each matched pair.

Exceptions

Type	Condition
ArgumentNullException	outer, inner, outerKeySelector, innerKeySelector, or resultSelector is null.

Last<TSource>(IOpt<TSource>)

Returns the first element of an option.

Declaration

public static TSource Last<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.

Returns

Type	Description
TSource	The first element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Last<TSource>(IOpt<TSource>, Func<TSource, Boolean>)

Returns the first element of an option that satisfies a condition.

Declaration

public static TSource Last<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.

Returns

Type	Description
TSource	The first element of source that satisfies predicate.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source does not contain any element that satisfies predicate.

LastOrDefault<TSource>(IOpt<TSource>)

Returns the first element of an option, or the default value for the type if the option is empty.

Declaration

public static TSource LastOrDefault<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.

Returns

Type	Description
TSource	The first element of source, or the default value for TSource if source is empty.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

LastOrDefault<TSource>(IOpt<TSource>, TSource)

Returns the first element of an option, or a specified default value if the option is empty.

Declaration

public static TSource LastOrDefault<TSource>(this IOpt<TSource> source, TSource defaultValue)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
TSource	defaultValue	A default value to return if source contains no elements.

Returns

Type	Description
TSource	The first element of source, or defaultValue if source is empty.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

LastOrDefault<TSource>(IOpt<TSource>, Func<TSource, Boolean>)

Returns the first element of an option that satisfies a condition, or the default value for the type if no such element is found.

Declaration

public static TSource LastOrDefault<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.

Returns

Type	Description
TSource	The first element of source that satisfies predicate, or the default value for TSource if no such element is found.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

LastOrDefault<TSource>(IOpt<TSource>, Func<TSource, Boolean>, TSource)

Returns the first element of an option that satisfies a condition, or a specified default value if no such element is found.

Declaration

public static TSource LastOrDefault<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate, TSource defaultValue)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.
TSource	defaultValue	A default value to return if source contains no elements that satisfy predicate.

Returns

Type	Description
TSource	The first element of source that satisfies predicate, or defaultValue if no such element is found.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

LongCount<TSource>(IOpt<TSource>)

Returns the number of elements in an option.

Declaration

public static long LongCount<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.

Returns

Type	Description
Int64	1 if source contains an element; otherwise, 0.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

LongCount<TSource>(IOpt<TSource>, Func<TSource, Boolean>)

Returns the number of elements of an option that satisfy a predicate.

Declaration

public static long LongCount<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.

Returns

Type	Description
Int64	1, if source contains an element that satisfies predicate; otherwise, 0.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

Match<TSource, TResult>(IOpt<TSource>, Func<TResult>, Func<TSource, TResult>)

Converts this option to another value based on its contents.

Declaration

public static TResult Match<TSource, TResult>(this IOpt<TSource> source, Func<TResult> ifEmpty = null, Func<TSource, TResult> ifFull = null)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TResult>	ifEmpty	A function to produce the result if this option is empty.
Func<TSource, TResult>	ifFull	A function to produce the result if this option is full, which accepts the contained element as a parameter.

Returns

Type	Description
TResult	The result of calling ifEmpty, if this option is empty; otherwise, the result of calling ifFull.

Type Parameters

Name	Description
TSource	The element type of source.
TResult	The result type for this conversion.

Remarks

This operation is performed immediately rather than by deferred execution. Compare MatchOpt<TSource, TResult>(IOpt<TSource>, Func<Opt<TResult>>, Func<TSource, Opt<TResult>>), which uses deferred execution.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	ifEmpty is null and this option is empty, or ifFull is null and this option is full.

MatchOpt<TSource, TResult>(IOpt<TSource>, Func<Opt<TResult>>, Func<TSource, Opt<TResult>>)

Converts this option to another option based on its contents.

Declaration

public static IOpt<TResult> MatchOpt<TSource, TResult>(this IOpt<TSource> source, Func<Opt<TResult>> ifEmpty = null, Func<TSource, Opt<TResult>> ifFull = null)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<Opt<TResult>>	ifEmpty	A function to produce the result if this option is empty.
Func<TSource, Opt<TResult>>	ifFull	A function to produce the result if this option is full, which accepts the contained element as a parameter.

Returns

Type	Description
IOpt<TResult>	An option equivalent to the result of calling ifEmpty, if this option is empty; otherwise, an option equivalent to the result of calling ifFull.

Type Parameters

Name	Description
TSource	The element type of source.
TResult	The element type for the result of this conversion.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Compare Match<TSource, TResult>(IOpt<TSource>, Func<TResult>, Func<TSource, TResult>), which uses immediate execution.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	ifEmpty is null and this option is empty, or ifFull is null and this option is full.

Max(IOpt<Decimal>)

Returns the maximum value in an option.

Declaration

public static decimal Max(this IOpt<decimal> source)

Parameters

Type	Name	Description
IOpt<Decimal>	source	A source option.

Returns

Type	Description
Decimal	The only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Max(IOpt<Double>)

Returns the maximum value in an option.

Declaration

public static double Max(this IOpt<double> source)

Parameters

Type	Name	Description
IOpt<Double>	source	A source option.

Returns

Type	Description
Double	The only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Max(IOpt<Int32>)

Returns the maximum value in an option.

Declaration

public static int Max(this IOpt<int> source)

Parameters

Type	Name	Description
IOpt<Int32>	source	A source option.

Returns

Type	Description
Int32	The only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Max(IOpt<Int64>)

Returns the maximum value in an option.

Declaration

public static long Max(this IOpt<long> source)

Parameters

Type	Name	Description
IOpt<Int64>	source	A source option.

Returns

Type	Description
Int64	The only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Max(IOpt<Nullable<Decimal>>)

Returns the maximum value in an option.

Declaration

public static decimal? Max(this IOpt<decimal? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Decimal>>	source	A source option.

Returns

Type	Description
Nullable<Decimal>	The only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Max(IOpt<Nullable<Double>>)

Returns the maximum value in an option.

Declaration

public static double? Max(this IOpt<double? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Double>>	source	A source option.

Returns

Type	Description
Nullable<Double>	The only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Max(IOpt<Nullable<Int32>>)

Returns the maximum value in an option.

Declaration

public static int? Max(this IOpt<int? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Int32>>	source	A source option.

Returns

Type	Description
Nullable<Int32>	The only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Max(IOpt<Nullable<Int64>>)

Returns the maximum value in an option.

Declaration

public static long? Max(this IOpt<long? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Int64>>	source	A source option.

Returns

Type	Description
Nullable<Int64>	The only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Max(IOpt<Nullable<Single>>)

Returns the maximum value in an option.

Declaration

public static float? Max(this IOpt<float? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Single>>	source	A source option.

Returns

Type	Description
Nullable<Single>	The only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Max(IOpt<Single>)

Returns the maximum value in an option.

Declaration

public static float Max(this IOpt<float> source)

Parameters

Type	Name	Description
IOpt<Single>	source	A source option.

Returns

Type	Description
Single	The only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Max<TSource>(IOpt<TSource>)

Returns the maximum value in an option.

Declaration

public static TSource Max<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.

Returns

Type	Description
TSource	The only element of source, if source contains a value; otherwise, null, if null is an allowed value for TSource.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty and null is not an allowed value for TSource.

Max<TSource>(IOpt<TSource>, Func<TSource, Decimal>)

Returns the maximum value in the projection of an option.

Declaration

public static decimal Max<TSource>(this IOpt<TSource> source, Func<TSource, decimal> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Decimal>	selector	A transform function applied to each element of source.

Returns

Type	Description
Decimal	The result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Max<TSource>(IOpt<TSource>, Func<TSource, Double>)

Returns the maximum value in the projection of an option.

Declaration

public static double Max<TSource>(this IOpt<TSource> source, Func<TSource, double> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Double>	selector	A transform function applied to each element of source.

Returns

Type	Description
Double	The result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Max<TSource>(IOpt<TSource>, Func<TSource, Int32>)

Returns the maximum value in the projection of an option.

Declaration

public static int Max<TSource>(this IOpt<TSource> source, Func<TSource, int> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Int32>	selector	A transform function applied to each element of source.

Returns

Type	Description
Int32	The result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Max<TSource>(IOpt<TSource>, Func<TSource, Int64>)

Returns the maximum value in the projection of an option.

Declaration

public static long Max<TSource>(this IOpt<TSource> source, Func<TSource, long> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Int64>	selector	A transform function applied to each element of source.

Returns

Type	Description
Int64	The result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Max<TSource>(IOpt<TSource>, Func<TSource, Nullable<Decimal>>)

Returns the maximum value in the projection of an option.

Declaration

public static decimal? Max<TSource>(this IOpt<TSource> source, Func<TSource, decimal? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Decimal>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Decimal>	The result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Max<TSource>(IOpt<TSource>, Func<TSource, Nullable<Double>>)

Returns the maximum value in the projection of an option.

Declaration

public static double? Max<TSource>(this IOpt<TSource> source, Func<TSource, double? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Double>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Double>	The result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Max<TSource>(IOpt<TSource>, Func<TSource, Nullable<Int32>>)

Returns the maximum value in the projection of an option.

Declaration

public static int? Max<TSource>(this IOpt<TSource> source, Func<TSource, int? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Int32>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Int32>	The result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Max<TSource>(IOpt<TSource>, Func<TSource, Nullable<Int64>>)

Returns the maximum value in the projection of an option.

Declaration

public static long? Max<TSource>(this IOpt<TSource> source, Func<TSource, long? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Int64>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Int64>	The result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Max<TSource>(IOpt<TSource>, Func<TSource, Nullable<Single>>)

Returns the maximum value in the projection of an option.

Declaration

public static float? Max<TSource>(this IOpt<TSource> source, Func<TSource, float? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Single>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Single>	The result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Max<TSource>(IOpt<TSource>, Func<TSource, Single>)

Returns the maximum value in the projection of an option.

Declaration

public static float Max<TSource>(this IOpt<TSource> source, Func<TSource, float> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Single>	selector	A transform function applied to each element of source.

Returns

Type	Description
Single	The result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Max<TSource, TResult>(IOpt<TSource>, Func<TSource, TResult>)

Returns the maximum value in the projection of an option.

Declaration

public static TResult Max<TSource, TResult>(this IOpt<TSource> source, Func<TSource, TResult> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TResult>	selector	A transform function applied to each element of source.

Returns

Type	Description
TResult	The result of applying selector to the only element of source, if source contains a value; otherwise, null, if null is an allowed value for TResult.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TResult

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty and null is not an allowed value for TResult.

Min(IOpt<Decimal>)

Returns the minimum value in an option.

Declaration

public static decimal Min(this IOpt<decimal> source)

Parameters

Type	Name	Description
IOpt<Decimal>	source	A source option.

Returns

Type	Description
Decimal	The only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Min(IOpt<Double>)

Returns the minimum value in an option.

Declaration

public static double Min(this IOpt<double> source)

Parameters

Type	Name	Description
IOpt<Double>	source	A source option.

Returns

Type	Description
Double	The only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Min(IOpt<Int32>)

Returns the minimum value in an option.

Declaration

public static int Min(this IOpt<int> source)

Parameters

Type	Name	Description
IOpt<Int32>	source	A source option.

Returns

Type	Description
Int32	The only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Min(IOpt<Int64>)

Returns the minimum value in an option.

Declaration

public static long Min(this IOpt<long> source)

Parameters

Type	Name	Description
IOpt<Int64>	source	A source option.

Returns

Type	Description
Int64	The only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Min(IOpt<Nullable<Decimal>>)

Returns the minimum value in an option.

Declaration

public static decimal? Min(this IOpt<decimal? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Decimal>>	source	A source option.

Returns

Type	Description
Nullable<Decimal>	The only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Min(IOpt<Nullable<Double>>)

Returns the minimum value in an option.

Declaration

public static double? Min(this IOpt<double? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Double>>	source	A source option.

Returns

Type	Description
Nullable<Double>	The only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Min(IOpt<Nullable<Int32>>)

Returns the minimum value in an option.

Declaration

public static int? Min(this IOpt<int? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Int32>>	source	A source option.

Returns

Type	Description
Nullable<Int32>	The only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Min(IOpt<Nullable<Int64>>)

Returns the minimum value in an option.

Declaration

public static long? Min(this IOpt<long? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Int64>>	source	A source option.

Returns

Type	Description
Nullable<Int64>	The only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Min(IOpt<Nullable<Single>>)

Returns the minimum value in an option.

Declaration

public static float? Min(this IOpt<float? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Single>>	source	A source option.

Returns

Type	Description
Nullable<Single>	The only element of source, if source contains a value; otherwise, null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Min(IOpt<Single>)

Returns the minimum value in an option.

Declaration

public static float Min(this IOpt<float> source)

Parameters

Type	Name	Description
IOpt<Single>	source	A source option.

Returns

Type	Description
Single	The only element of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Min<TSource>(IOpt<TSource>)

Returns the minimum value in an option.

Declaration

public static TSource Min<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.

Returns

Type	Description
TSource	The only element of source, if source contains a value; otherwise, null, if null is an allowed value for TSource.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty and null is not an allowed value for TSource.

Min<TSource>(IOpt<TSource>, Func<TSource, Decimal>)

Returns the minimum value in the projection of an option.

Declaration

public static decimal Min<TSource>(this IOpt<TSource> source, Func<TSource, decimal> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Decimal>	selector	A transform function applied to each element of source.

Returns

Type	Description
Decimal	The result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Min<TSource>(IOpt<TSource>, Func<TSource, Double>)

Returns the minimum value in the projection of an option.

Declaration

public static double Min<TSource>(this IOpt<TSource> source, Func<TSource, double> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Double>	selector	A transform function applied to each element of source.

Returns

Type	Description
Double	The result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Min<TSource>(IOpt<TSource>, Func<TSource, Int32>)

Returns the minimum value in the projection of an option.

Declaration

public static int Min<TSource>(this IOpt<TSource> source, Func<TSource, int> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Int32>	selector	A transform function applied to each element of source.

Returns

Type	Description
Int32	The result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Min<TSource>(IOpt<TSource>, Func<TSource, Int64>)

Returns the minimum value in the projection of an option.

Declaration

public static long Min<TSource>(this IOpt<TSource> source, Func<TSource, long> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Int64>	selector	A transform function applied to each element of source.

Returns

Type	Description
Int64	The result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Min<TSource>(IOpt<TSource>, Func<TSource, Nullable<Decimal>>)

Returns the minimum value in the projection of an option.

Declaration

public static decimal? Min<TSource>(this IOpt<TSource> source, Func<TSource, decimal? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Decimal>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Decimal>	The result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Min<TSource>(IOpt<TSource>, Func<TSource, Nullable<Double>>)

Returns the minimum value in the projection of an option.

Declaration

public static double? Min<TSource>(this IOpt<TSource> source, Func<TSource, double? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Double>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Double>	The result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Min<TSource>(IOpt<TSource>, Func<TSource, Nullable<Int32>>)

Returns the minimum value in the projection of an option.

Declaration

public static int? Min<TSource>(this IOpt<TSource> source, Func<TSource, int? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Int32>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Int32>	The result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Min<TSource>(IOpt<TSource>, Func<TSource, Nullable<Int64>>)

Returns the minimum value in the projection of an option.

Declaration

public static long? Min<TSource>(this IOpt<TSource> source, Func<TSource, long? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Int64>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Int64>	The result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Min<TSource>(IOpt<TSource>, Func<TSource, Nullable<Single>>)

Returns the minimum value in the projection of an option.

Declaration

public static float? Min<TSource>(this IOpt<TSource> source, Func<TSource, float? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Single>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Single>	The result of applying selector to the only element of source, if source contains a value; otherwise, null.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Min<TSource>(IOpt<TSource>, Func<TSource, Single>)

Returns the minimum value in the projection of an option.

Declaration

public static float Min<TSource>(this IOpt<TSource> source, Func<TSource, float> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Single>	selector	A transform function applied to each element of source.

Returns

Type	Description
Single	The result of applying selector to the only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Min<TSource, TResult>(IOpt<TSource>, Func<TSource, TResult>)

Returns the minimum value in the projection of an option.

Declaration

public static TResult Min<TSource, TResult>(this IOpt<TSource> source, Func<TSource, TResult> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TResult>	selector	A transform function applied to each element of source.

Returns

Type	Description
TResult	The result of applying selector to the only element of source, if source contains a value; otherwise, null, if null is an allowed value for TResult.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TResult

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty and null is not an allowed value for TResult.

OfType<TResult>(IOpt)

Filters the elements of an option to those of a specified type.

Declaration

public static IOpt<TResult> OfType<TResult>(this IOpt source)

Parameters

Type	Name	Description
IOpt	source	A source option.

Returns

Type	Description
IOpt<TResult>	An option having the same contents as source, if it contains an element that is of type TResult (according to the langword_csharp_is operator); otherwise, an empty option.

Type Parameters

Name	Description
TResult	The type to which to filter the elements of source.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source is null.

OrderBy<TSource, TKey>(IOpt<TSource>, Func<TSource, TKey>)

Sorts the elements of an option in ascending order.

Declaration

public static IOpt<TSource> OrderBy<TSource, TKey>(this IOpt<TSource> source, Func<TSource, TKey> keySelector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element of source.

Returns

Type	Description
IOpt<TSource>	source.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to compare elements.

Remarks

Since an option, by virtue of being a zero- or one-element sequence, is trivially already ordered, this method returns source unmodified (after null-checking any required parameters).

Exceptions

Type	Condition
ArgumentNullException	source or keySelector is null.

OrderBy<TSource, TKey>(IOpt<TSource>, Func<TSource, TKey>, IComparer<TKey>)

Sorts the elements of an option in ascending order.

Declaration

public static IOpt<TSource> OrderBy<TSource, TKey>(this IOpt<TSource> source, Func<TSource, TKey> keySelector, IComparer<TKey> comparer)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element of source.
IComparer<TKey>	comparer	A comparer used to order keys. (This parameter is ignored.)

Returns

Type	Description
IOpt<TSource>	source.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to compare elements.

Remarks

Since an option, by virtue of being a zero- or one-element sequence, is trivially already ordered, this method returns source unmodified (after null-checking any required parameters).

Exceptions

Type	Condition
ArgumentNullException	source or keySelector is null.

OrderByDescending<TSource, TKey>(IOpt<TSource>, Func<TSource, TKey>)

Sorts the elements of an option in descending order.

Declaration

public static IOpt<TSource> OrderByDescending<TSource, TKey>(this IOpt<TSource> source, Func<TSource, TKey> keySelector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element of source.

Returns

Type	Description
IOpt<TSource>	source.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to compare elements.

Remarks

Since an option, by virtue of being a zero- or one-element sequence, is trivially already ordered, this method returns source unmodified (after null-checking any required parameters).

Exceptions

Type	Condition
ArgumentNullException	source or keySelector is null.

OrderByDescending<TSource, TKey>(IOpt<TSource>, Func<TSource, TKey>, IComparer<TKey>)

Sorts the elements of an option in descending order.

Declaration

public static IOpt<TSource> OrderByDescending<TSource, TKey>(this IOpt<TSource> source, Func<TSource, TKey> keySelector, IComparer<TKey> comparer)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element of source.
IComparer<TKey>	comparer	A comparer used to order keys. (This parameter is ignored.)

Returns

Type	Description
IOpt<TSource>	source.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to compare elements.

Remarks

Since an option, by virtue of being a zero- or one-element sequence, is trivially already ordered, this method returns source unmodified (after null-checking any required parameters).

Exceptions

Type	Condition
ArgumentNullException	source or keySelector is null.

ReplaceIfEmpty<TSource>(IOpt<TSource>, IOpt<TSource>)

Substitutes the specified replacement option if this option is empty.

Declaration

public static IOpt<TSource> ReplaceIfEmpty<TSource>(this IOpt<TSource> source, IOpt<TSource> replacement)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
IOpt<TSource>	replacement	An option to produce the result if source is empty.

Returns

Type	Description
IOpt<TSource>	An option equivalent to source, if it is full; otherwise, an option equivalent to replacement.

Type Parameters

Name	Description
TSource	The element type of source.

Exceptions

Type	Condition
ArgumentNullException	source or replacement is null.

ReplaceIfEmpty<TSource>(IOpt<TSource>, Func<IOpt<TSource>>)

Substitutes the result of a callback if this option is empty.

Declaration

public static IOpt<TSource> ReplaceIfEmpty<TSource>(this IOpt<TSource> source, Func<IOpt<TSource>> replacementFactory)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<IOpt<TSource>>	replacementFactory	A function to produce the result if source is empty.

Returns

Type	Description
IOpt<TSource>	An option equivalent to source, if it is full; otherwise, an option equivalent to the result of calling replacementFactory.

Type Parameters

Name	Description
TSource	The element type of source.

Exceptions

Type	Condition
ArgumentNullException	source or replacementFactory is null.

Reverse<TSource>(IOpt<TSource>)

Inverts the order of contents of an option.

Declaration

public static IOpt<TSource> Reverse<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.

Returns

Type	Description
IOpt<TSource>	source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

Since an option, by virtue of being a zero- or one-element sequence, is its own reverse, this method returns source unmodified (after ensuring that it is not null).

Exceptions

Type	Condition
ArgumentNullException	source is null.

Select<TSource, TResult>(IOpt<TSource>, Func<TSource, TResult>)

Produces a projection of an option by applying a transformation function to its contents.

Declaration

public static IOpt<TResult> Select<TSource, TResult>(this IOpt<TSource> source, Func<TSource, TResult> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TResult>	selector	A transform function applied to each element of source.

Returns

Type	Description
IOpt<TResult>	A full option containing the result of applying selector to the element of source, if source is full; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TResult	The type of the elements of the result option.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source or selector is null.

Select<TSource, TResult>(IOpt<TSource>, Func<TSource, Int32, TResult>)

Produces a projection of an option by applying a transformation function to its contents.

Declaration

public static IOpt<TResult> Select<TSource, TResult>(this IOpt<TSource> source, Func<TSource, int, TResult> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Int32, TResult>	selector	A transform function applied to each element of source and its index.

Returns

Type	Description
IOpt<TResult>	A full option containing the result of applying selector to the element of source and its index, if source is full; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TResult	The type of the elements of the result option.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source or selector is null.

SelectMany<TSource, TResult>(IOpt<TSource>, Func<TSource, IOpt<TResult>>)

Projects each element of an option to a new option and flattens the result.

Declaration

public static IOpt<TResult> SelectMany<TSource, TResult>(this IOpt<TSource> source, Func<TSource, IOpt<TResult>> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, IOpt<TResult>>	selector	A transform function applied to each element of source.

Returns

Type	Description
IOpt<TResult>	A full option equivalent to the result of applying selector to the element of source, if source is full; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TResult	The type of the elements of the option returned by selector.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source or selector is null.

SelectMany<TSource, TResult>(IOpt<TSource>, Func<TSource, Int32, IOpt<TResult>>)

Projects each element of an option to a new option and flattens the result.

Declaration

public static IOpt<TResult> SelectMany<TSource, TResult>(this IOpt<TSource> source, Func<TSource, int, IOpt<TResult>> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Int32, IOpt<TResult>>	selector	A transform function applied to each element of source and its index.

Returns

Type	Description
IOpt<TResult>	A full option equivalent to the result of applying selector to the element of source and its index, if source is full; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TResult	The type of the elements of the option returned by selector.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source or selector is null.

SelectMany<TSource, TCollection, TResult>(IOpt<TSource>, Func<TSource, IOpt<TCollection>>, Func<TSource, TCollection, TResult>)

Projects each element of an option to a new option and flattens the result, then applies a transform to the result elements.

Declaration

public static IOpt<TResult> SelectMany<TSource, TCollection, TResult>(this IOpt<TSource> source, Func<TSource, IOpt<TCollection>> collectionSelector, Func<TSource, TCollection, TResult> resultSelector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, IOpt<TCollection>>	collectionSelector	A transform function applied to each element of source.
Func<TSource, TCollection, TResult>	resultSelector	A transform function applied to each element of each intermediate option returned by collectionSelector and its corresponding element from source.

Returns

Type	Description
IOpt<TResult>	A full option containing the result of applying resultSelector to the element of source and the element of the intermediate option produced by applying collectionSelector to the element of source, if source is full and the intermediate option is also full; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TCollection	The type of the elements of the intermediate option produced by applying collectionSelector to an element of source.
TResult	The type of the elements of the result option.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source, collectionSelector, or resultSelector is null.

SelectMany<TSource, TCollection, TResult>(IOpt<TSource>, Func<TSource, Int32, IOpt<TCollection>>, Func<TSource, TCollection, TResult>)

Projects each element of an option to a new option and flattens the result, then applies a transform to the result elements.

Declaration

public static IOpt<TResult> SelectMany<TSource, TCollection, TResult>(this IOpt<TSource> source, Func<TSource, int, IOpt<TCollection>> collectionSelector, Func<TSource, TCollection, TResult> resultSelector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Int32, IOpt<TCollection>>	collectionSelector	A transform function applied to each element of source.
Func<TSource, TCollection, TResult>	resultSelector	A transform function applied to each element of each intermediate option returned by collectionSelector and its corresponding element from source.

Returns

Type	Description
IOpt<TResult>	A full option containing the result of applying resultSelector to the element of source and the element of the intermediate option produced by applying collectionSelector to the element of source and its index, if source is full and the intermediate option is also full; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TCollection	The type of the elements of the intermediate option produced by applying collectionSelector to an element of source and its index.
TResult	The type of the elements of the result option.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source, collectionSelector, or resultSelector is null.

SequenceEqual<TSource>(IOpt<TSource>, IEnumerable<TSource>)

Determines whether an option has an equal length and sequence of elements to a sequence.

Declaration

public static bool SequenceEqual<TSource>(this IOpt<TSource> first, IEnumerable<TSource> second)

Parameters

Type	Name	Description
IOpt<TSource>	first	A source option.
IEnumerable<TSource>	second	A sequence whose contents to compare with those of first.

Returns

Type	Description
Boolean	true if first and second are both empty or each of first and second contains exactly one element and those elements are equal; otherwise, false.

Type Parameters

Name	Description
TSource	The type of the elements of first and second.

Exceptions

Type	Condition
ArgumentNullException	first or second is null.

SequenceEqual<TSource>(IOpt<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)

Determines whether an option has an equal length and sequence of elements to a sequence.

Declaration

public static bool SequenceEqual<TSource>(this IOpt<TSource> first, IEnumerable<TSource> second, IEqualityComparer<TSource> comparer)

Parameters

Type	Name	Description
IOpt<TSource>	first	A source option.
IEnumerable<TSource>	second	A sequence whose contents to compare with those of first.
IEqualityComparer<TSource>	comparer	A comparer to determine whether values are equal. (If null, Default is used.)

Returns

Type	Description
Boolean	true if first and second are both empty or each of first and second contains exactly one element and those elements are equal; otherwise, false.

Type Parameters

Name	Description
TSource	The type of the elements of first and second.

Exceptions

Type	Condition
ArgumentNullException	first or second is null.

Single<TSource>(IOpt<TSource>)

Returns the only element of an option.

Declaration

public static TSource Single<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.

Returns

Type	Description
TSource	The only element of source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source is empty.

Single<TSource>(IOpt<TSource>, Func<TSource, Boolean>)

Returns the only element of an option that satisfies a condition.

Declaration

public static TSource Single<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.

Returns

Type	Description
TSource	The only element of source that satisfies predicate.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.
InvalidOperationException	source does not contain any element that satisfies predicate.

SingleOrDefault<TSource>(IOpt<TSource>)

Returns the only element of an option, or the default value for the type if the option is empty.

Declaration

public static TSource SingleOrDefault<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.

Returns

Type	Description
TSource	The only element of source, or the default value for TSource if source is empty.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

SingleOrDefault<TSource>(IOpt<TSource>, TSource)

Returns the only element of an option, or a specified default value if the option is empty.

Declaration

public static TSource SingleOrDefault<TSource>(this IOpt<TSource> source, TSource defaultValue)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
TSource	defaultValue	A default value to return if source contains no elements.

Returns

Type	Description
TSource	The only element of source, or defaultValue if source is empty.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

SingleOrDefault<TSource>(IOpt<TSource>, Func<TSource, Boolean>)

Returns the only element of an option that satisfies a condition, or the default value for the type if no such element is found.

Declaration

public static TSource SingleOrDefault<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.

Returns

Type	Description
TSource	The only element of source that satisfies predicate, or the default value for TSource if no such element is found.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

SingleOrDefault<TSource>(IOpt<TSource>, Func<TSource, Boolean>, TSource)

Returns the only element of an option that satisfies a condition, or a specified default value if no such element is found.

Declaration

public static TSource SingleOrDefault<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate, TSource defaultValue)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to return an element from.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.
TSource	defaultValue	A default value to return if source contains no elements that satisfy predicate.

Returns

Type	Description
TSource	The only element of source that satisfies predicate, or defaultValue if no such element is found.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

Skip<TSource>(IOpt<TSource>, Int32)

Returns the remaining contents of an option after skipping a specified number of elements.

Declaration

public static IOpt<TSource> Skip<TSource>(this IOpt<TSource> source, int count)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Int32	count	The number of elements to skip.

Returns

Type	Description
IOpt<TSource>	source, if count is less than or equal to 0; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

If count is zero or negative, no elements are skipped. If count is greater than or equal to the number of elements of source, all elements are skipped.

Exceptions

Type	Condition
ArgumentNullException	source is null.

SkipWhile<TSource>(IOpt<TSource>, Func<TSource, Boolean>)

Returns the first element of an option that does not satisfy a predicate and all following elements.

Declaration

public static IOpt<TSource> SkipWhile<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.

Returns

Type	Description
IOpt<TSource>	An empty option, if source is empty or contains an element that satisfies predicate; otherwise, an option with the same contents as source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

If all elements of source satisfy predicate, the result is empty.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

SkipWhile<TSource>(IOpt<TSource>, Func<TSource, Int32, Boolean>)

Returns the first element of an option that does not satisfy a predicate and all following elements.

Declaration

public static IOpt<TSource> SkipWhile<TSource>(this IOpt<TSource> source, Func<TSource, int, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Int32, Boolean>	predicate	A function to test each element and its index for a condition.

Returns

Type	Description
IOpt<TSource>	An empty option, if source is empty or contains an element that satisfies predicate; otherwise, an option with the same contents as source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

If all elements of source satisfy predicate, the result is empty.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

Sum(IOpt<Decimal>)

Computes the sum of the contents of an option.

Declaration

public static decimal Sum(this IOpt<decimal> source)

Parameters

Type	Name	Description
IOpt<Decimal>	source	A source option.

Returns

Type	Description
Decimal	The value of the only element of source, or zero if source is empty.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Sum(IOpt<Double>)

Computes the sum of the contents of an option.

Declaration

public static double Sum(this IOpt<double> source)

Parameters

Type	Name	Description
IOpt<Double>	source	A source option.

Returns

Type	Description
Double	The value of the only element of source, or zero if source is empty.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Sum(IOpt<Int32>)

Computes the sum of the contents of an option.

Declaration

public static int Sum(this IOpt<int> source)

Parameters

Type	Name	Description
IOpt<Int32>	source	A source option.

Returns

Type	Description
Int32	The value of the only element of source, or zero if source is empty.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Sum(IOpt<Int64>)

Computes the sum of the contents of an option.

Declaration

public static long Sum(this IOpt<long> source)

Parameters

Type	Name	Description
IOpt<Int64>	source	A source option.

Returns

Type	Description
Int64	The value of the only element of source, or zero if source is empty.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Sum(IOpt<Nullable<Decimal>>)

Computes the sum of the non-null contents of an option.

Declaration

public static decimal? Sum(this IOpt<decimal? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Decimal>>	source	A source option.

Returns

Type	Description
Nullable<Decimal>	The value of the only element of source, or zero if source is empty or contains null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Sum(IOpt<Nullable<Double>>)

Computes the sum of the non-null contents of an option.

Declaration

public static double? Sum(this IOpt<double? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Double>>	source	A source option.

Returns

Type	Description
Nullable<Double>	The value of the only element of source, or zero if source is empty or contains null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Sum(IOpt<Nullable<Int32>>)

Computes the sum of the non-null contents of an option.

Declaration

public static int? Sum(this IOpt<int? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Int32>>	source	A source option.

Returns

Type	Description
Nullable<Int32>	The value of the only element of source, or zero if source is empty or contains null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Sum(IOpt<Nullable<Int64>>)

Computes the sum of the non-null contents of an option.

Declaration

public static long? Sum(this IOpt<long? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Int64>>	source	A source option.

Returns

Type	Description
Nullable<Int64>	The value of the only element of source, or zero if source is empty or contains null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Sum(IOpt<Nullable<Single>>)

Computes the sum of the non-null contents of an option.

Declaration

public static float? Sum(this IOpt<float? > source)

Parameters

Type	Name	Description
IOpt<Nullable<Single>>	source	A source option.

Returns

Type	Description
Nullable<Single>	The value of the only element of source, or zero if source is empty or contains null.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Sum(IOpt<Single>)

Computes the sum of the contents of an option.

Declaration

public static float Sum(this IOpt<float> source)

Parameters

Type	Name	Description
IOpt<Single>	source	A source option.

Returns

Type	Description
Single	The value of the only element of source, or zero if source is empty.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Sum<TSource>(IOpt<TSource>, Func<TSource, Decimal>)

Computes the sum of a projection of the contents of an option.

Declaration

public static decimal Sum<TSource>(this IOpt<TSource> source, Func<TSource, decimal> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Decimal>	selector	A transform function applied to each element of source.

Returns

Type	Description
Decimal	The value of the result of applying selector to the only element of source, or zero if source is empty.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Sum<TSource>(IOpt<TSource>, Func<TSource, Double>)

Computes the sum of a projection of the contents of an option.

Declaration

public static double Sum<TSource>(this IOpt<TSource> source, Func<TSource, double> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Double>	selector	A transform function applied to each element of source.

Returns

Type	Description
Double	The value of the result of applying selector to the only element of source, or zero if source is empty.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Sum<TSource>(IOpt<TSource>, Func<TSource, Int32>)

Computes the sum of a projection of the contents of an option.

Declaration

public static int Sum<TSource>(this IOpt<TSource> source, Func<TSource, int> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Int32>	selector	A transform function applied to each element of source.

Returns

Type	Description
Int32	The value of the result of applying selector to the only element of source, or zero if source is empty.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Sum<TSource>(IOpt<TSource>, Func<TSource, Int64>)

Computes the sum of a projection of the contents of an option.

Declaration

public static long Sum<TSource>(this IOpt<TSource> source, Func<TSource, long> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Int64>	selector	A transform function applied to each element of source.

Returns

Type	Description
Int64	The value of the result of applying selector to the only element of source, or zero if source is empty.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Sum<TSource>(IOpt<TSource>, Func<TSource, Nullable<Decimal>>)

Computes the sum of the non-null elements of a projection of the contents of an option.

Declaration

public static decimal? Sum<TSource>(this IOpt<TSource> source, Func<TSource, decimal? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Decimal>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Decimal>	The value of the result of applying selector to the only element of source, source contains a value and that result is not null; otherwise, zero.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Sum<TSource>(IOpt<TSource>, Func<TSource, Nullable<Double>>)

Computes the sum of the non-null elements of a projection of the contents of an option.

Declaration

public static double? Sum<TSource>(this IOpt<TSource> source, Func<TSource, double? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Double>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Double>	The value of the result of applying selector to the only element of source, source contains a value and that result is not null; otherwise, zero.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Sum<TSource>(IOpt<TSource>, Func<TSource, Nullable<Int32>>)

Computes the sum of the non-null elements of a projection of the contents of an option.

Declaration

public static int? Sum<TSource>(this IOpt<TSource> source, Func<TSource, int? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Int32>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Int32>	The value of the result of applying selector to the only element of source, source contains a value and that result is not null; otherwise, zero.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Sum<TSource>(IOpt<TSource>, Func<TSource, Nullable<Int64>>)

Computes the sum of the non-null elements of a projection of the contents of an option.

Declaration

public static long? Sum<TSource>(this IOpt<TSource> source, Func<TSource, long? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Int64>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Int64>	The value of the result of applying selector to the only element of source, source contains a value and that result is not null; otherwise, zero.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Sum<TSource>(IOpt<TSource>, Func<TSource, Nullable<Single>>)

Computes the sum of the non-null elements of a projection of the contents of an option.

Declaration

public static float? Sum<TSource>(this IOpt<TSource> source, Func<TSource, float? > selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Nullable<Single>>	selector	A transform function applied to each element of source.

Returns

Type	Description
Nullable<Single>	The value of the result of applying selector to the only element of source, source contains a value and that result is not null; otherwise, zero.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Sum<TSource>(IOpt<TSource>, Func<TSource, Single>)

Computes the sum of a projection of the contents of an option.

Declaration

public static float Sum<TSource>(this IOpt<TSource> source, Func<TSource, float> selector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Single>	selector	A transform function applied to each element of source.

Returns

Type	Description
Single	The value of the result of applying selector to the only element of source, or zero if source is empty.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Take<TSource>(IOpt<TSource>, Int32)

Returns the specified number of elements from an option.

Declaration

public static IOpt<TSource> Take<TSource>(this IOpt<TSource> source, int count)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Int32	count	The number of elements to return.

Returns

Type	Description
IOpt<TSource>

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

If count is zero or negative, no elements are returned. If count is greater than or equal to the number of elements of source, all elements are returned.

Exceptions

Type	Condition
ArgumentNullException	source is null.

TakeWhile<TSource>(IOpt<TSource>, Func<TSource, Boolean>)

Returns all elements of an option before the first element that does not satisfy a predicate.

Declaration

public static IOpt<TSource> TakeWhile<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Boolean>	predicate	A function to test each element for a condition.

Returns

Type	Description
IOpt<TSource>	An empty option, if source is empty or contains an element that does not satisfy predicate; otherwise, an option with the same contents as source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

If no elements of source satisfy predicate, the result is empty.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

TakeWhile<TSource>(IOpt<TSource>, Func<TSource, Int32, Boolean>)

Returns all elements of an option before the first element that does not satisfy a predicate.

Declaration

public static IOpt<TSource> TakeWhile<TSource>(this IOpt<TSource> source, Func<TSource, int, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Int32, Boolean>	predicate	A function to test each element and its index for a condition.

Returns

Type	Description
IOpt<TSource>	An empty option, if source is empty or contains an element that does not satisfy predicate; otherwise, an option with the same contents as source.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

ThenBy<TSource, TKey>(IOpt<TSource>, Func<TSource, TKey>)

Subsequently sorts the elements of an already ordered option in ascending order.

Declaration

public static IOpt<TSource> ThenBy<TSource, TKey>(this IOpt<TSource> source, Func<TSource, TKey> keySelector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element of source.

Returns

Type	Description
IOpt<TSource>	source.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to compare elements.

Remarks

Since an option, by virtue of being a zero- or one-element sequence, is trivially already ordered, this method returns source unmodified (after null-checking any required parameters).

Exceptions

Type	Condition
ArgumentNullException	source or keySelector is null.

ThenBy<TSource, TKey>(IOpt<TSource>, Func<TSource, TKey>, IComparer<TKey>)

Subsequently sorts the elements of an already ordered option in ascending order.

Declaration

public static IOpt<TSource> ThenBy<TSource, TKey>(this IOpt<TSource> source, Func<TSource, TKey> keySelector, IComparer<TKey> comparer)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element of source.
IComparer<TKey>	comparer	A comparer used to order keys. (This parameter is ignored.)

Returns

Type	Description
IOpt<TSource>	source.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to compare elements.

Remarks

Since an option, by virtue of being a zero- or one-element sequence, is trivially already ordered, this method returns source unmodified (after null-checking any required parameters).

Exceptions

Type	Condition
ArgumentNullException	source or keySelector is null.

ThenByDescending<TSource, TKey>(IOpt<TSource>, Func<TSource, TKey>)

Subsequently sorts the elements of an already ordered option in descending order.

Declaration

public static IOpt<TSource> ThenByDescending<TSource, TKey>(this IOpt<TSource> source, Func<TSource, TKey> keySelector)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element of source.

Returns

Type	Description
IOpt<TSource>	source.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to compare elements.

Remarks

Since an option, by virtue of being a zero- or one-element sequence, is trivially already ordered, this method returns source unmodified (after null-checking any required parameters).

Exceptions

Type	Condition
ArgumentNullException	source or keySelector is null.

ThenByDescending<TSource, TKey>(IOpt<TSource>, Func<TSource, TKey>, IComparer<TKey>)

Subsequently sorts the elements of an already ordered option in descending order.

Declaration

public static IOpt<TSource> ThenByDescending<TSource, TKey>(this IOpt<TSource> source, Func<TSource, TKey> keySelector, IComparer<TKey> comparer)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, TKey>	keySelector	A function to select the key that corresponds to an element of source.
IComparer<TKey>	comparer	A comparer used to order keys. (This parameter is ignored.)

Returns

Type	Description
IOpt<TSource>	source.

Type Parameters

Name	Description
TSource	The type of the elements of source.
TKey	The type of the key used to compare elements.

Remarks

Since an option, by virtue of being a zero- or one-element sequence, is trivially already ordered, this method returns source unmodified (after null-checking any required parameters).

Exceptions

Type	Condition
ArgumentNullException	source or keySelector is null.

ToArray<TSource>(IOpt<TSource>)

Creates a new array having the same contents as an option.

Declaration

public static TSource[] ToArray<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.

Returns

Type	Description
TSource[]	A new single-element array containing the element of source, if it is not empty; otherwise, a new zero-element array.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

ToFixed(IOpt)

Returns a fixed option reflecting the current state of an option.

Declaration

public static Opt<object> ToFixed(this IOpt source)

Parameters

Type	Name	Description
IOpt	source	A source option.

Returns

Type	Description
Opt<Object>	A fixed option reflecting the current state of source.

ToFixed<TSource>(IOpt<TSource>)

Returns a fixed option reflecting the current state of an option.

Declaration

public static Opt<TSource> ToFixed<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.

Returns

Type	Description
Opt<TSource>	A fixed option reflecting the current state of source.

Type Parameters

Name	Description
TSource	The element type of source.

ToList<TSource>(IOpt<TSource>)

Creates a new list having the same contents as an option.

Declaration

public static List<TSource> ToList<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.

Returns

Type	Description
List<TSource>	A new single-element list containing the element of source, if it is not empty; otherwise, a new empty list.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

TryGetValue<TSource>(IOpt<TSource>, out TSource)

Gets the value contained by an option, if it exists.

Declaration

public static bool TryGetValue<TSource>(this IOpt<TSource> source, out TSource value)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option whose value to get.
TSource	value	When this method returns, is set to the value contained by source, if any, or the default value of TSource, otherwise.

Returns

Type	Description
Boolean	true, if source contains a value; otherwise, false.

Type Parameters

Name	Description
TSource	The element type of source.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Where<TSource>(IOpt<TSource>, Func<TSource, Boolean>)

Filters the elements of an option to those that satisfy a predicate.

Declaration

public static IOpt<TSource> Where<TSource>(this IOpt<TSource> source, Func<TSource, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Boolean>	predicate	A function to test an element of source.

Returns

Type	Description
IOpt<TSource>	An option containing the same element as source, if source is full and its element satisfies predicate; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

Where<TSource>(IOpt<TSource>, Func<TSource, Int32, Boolean>)

Filters the elements of an option to those that satisfy a predicate.

Declaration

public static IOpt<TSource> Where<TSource>(this IOpt<TSource> source, Func<TSource, int, bool> predicate)

Parameters

Type	Name	Description
IOpt<TSource>	source	A source option.
Func<TSource, Int32, Boolean>	predicate	A function to test an element of source and its index.

Returns

Type	Description
IOpt<TSource>	An option containing the same element as source, if source is full and its element and index satisfy predicate; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source or predicate is null.

WhereNotNull<TSource>(IOpt<TSource>)

Filters the contents of an option to include only non- null values.

Declaration

public static IOpt<TSource> WhereNotNull<TSource>(this IOpt<TSource> source)

Parameters

Type	Name	Description
IOpt<TSource>	source	An option to filter.

Returns

Type	Description
IOpt<TSource>	An option equivalent to source, if it is full and contains a non- null value; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The type of the elements of source.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source is null.

WhereNotNullSelectValue<TSource>(IOpt<Nullable<TSource>>)

Filters the contents of an option to include only non- null values, converting the results to their non-nullable type.

Declaration

public static IOpt<TSource> WhereNotNullSelectValue<TSource>(this IOpt<TSource? > source)
    where TSource : struct

Parameters

Type	Name	Description
IOpt<Nullable<TSource>>	source	An option to filter.

Returns

Type	Description
IOpt<TSource>	An option containing the same value as source, if it is full and contains a non- null value; otherwise, an empty option.

Type Parameters

Name	Description
TSource	The non-nullable basis type of the type of the elements of source.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	source is null.

Zip<TFirst, TSecond, TResult>(IOpt<TFirst>, IEnumerable<TSecond>, Func<TFirst, TSecond, TResult>)

Produces a new option by combining the value from an option with the value from another source using the specified result selector.

Declaration

public static IOpt<TResult> Zip<TFirst, TSecond, TResult>(this IOpt<TFirst> first, IEnumerable<TSecond> second, Func<TFirst, TSecond, TResult> resultSelector)

Parameters

Type	Name	Description
IOpt<TFirst>	first	The first source.
IEnumerable<TSecond>	second	The second source.
Func<TFirst, TSecond, TResult>	resultSelector	A function that specifies how to combine an element from first with the corresponding element of second.

Returns

Type	Description
IOpt<TResult>	An option containing the result of calling resultSelector on the element of first and the first element of second, or an empty option if either first or second is empty.

Type Parameters

Name	Description
TFirst	The type of the elements of first.
TSecond	The type of the elements of second.
TResult	The type of the elements of the result option.

Remarks

This method is implemented using deferred execution; the query represented by this method is not performed until the contents of the returned option are resolved, such as by enumeration.

Exceptions

Type	Condition
ArgumentNullException	first or second is null.