System.Linq.Async

An iterator that can produce an array or through an optimized path.

This interface is primarily used for internal purposes as an optimization for LINQ operators. It was made public because it was defined in the System.Linq.Async package but also used in System.Interactive.Async. Now that System.Linq.Async is being retired in favor of .NET 10.0's System.Linq.AsyncEnumerable, the System.Interactive.Async package no longer takes a dependency on System.Linq.Async, and therefore defines its own version of this interface. We can't replace this with a type forwarder here because that would risk creating a circular dependency in cases where an application managed to get out-of-sync versions of the two packages.

Produce an array of the sequence through an optimized path.

The array.

Produce a of the sequence through an optimized path.

The .

Returns the count of elements in the sequence.

If true then the count should only be calculated if doing so is quick (sure or likely to be constant time), otherwise -1 should be returned. The number of elements.

An iterator that supports random access and can produce a partial sequence of its items through an optimized path.

Creates a new partition that skips the specified number of elements from this sequence.

The number of elements to skip. An with the first items removed.

Creates a new partition that takes the specified number of elements from this sequence.

The number of elements to take. An with only the first items.

Gets the item associated with a 0-based index in this sequence.

The 0-based index to access. Token to observe for cancellation requests. The element if found, otherwise, the default value of .

Gets the first item in this sequence.

Token to observe for cancellation requests. The element if found, otherwise, the default value of .

Gets the last item in this sequence.

Token to observe for cancellation requests. The element if found, otherwise, the default value of .

Applies an accumulator function over an async-enumerable sequence, returning the result of the aggregation as a single element in the result sequence.

The type of elements in the source sequence. An async-enumerable sequence to aggregate over. An asynchronous accumulator function to be invoked and awaited on each element. An optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing the final accumulator value. or is . The source sequence is empty. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Applies an accumulator function over an async-enumerable sequence, returning the result of the aggregation as a single element in the result sequence. The specified seed value is used as the initial accumulator value.

The type of elements in the source sequence. The type of the result of aggregation. An async-enumerable sequence to aggregate over. The initial accumulator value. An asynchronous accumulator function to be invoked and awaited on each element. An optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing the final accumulator value. or is . The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

The type of elements in the source sequence. The type of the accumulator value. The type of the resulting value. An async-enumerable sequence to aggregate over. The initial accumulator value. An asynchronous accumulator function to be invoked and awaited on each element. An asynchronous transform function to transform the final accumulator value into the result value. An optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing the value obtained by applying the result selector to the final accumulator value. or or is .

Determines whether all elements in an async-enumerable sequence satisfy a condition.

The type of element in the sequence. An async-enumerable sequence whose elements to apply the predicate to. An asynchronous predicate to apply to each element of the source sequence. An optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing a value indicating whether all elements in the sequence pass the test in the specified predicate. or is . The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Determines whether any element in an async-enumerable sequence satisfies a condition.

The type of element in the sequence. An async-enumerable sequence whose elements to apply the predicate to. An asynchronous predicate to apply to each element of the source sequence. An optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing a value indicating whether any elements in the source sequence pass the test in the specified predicate. or is . The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Computes the average of an async-enumerable sequence of values that are obtained by invoking an asynchronous transform function on each element of the source sequence and awaiting the result.

The type of elements in the source sequence. An async-enumerable sequence of values to compute the average of. A transform function to invoke and await on each element of the source sequence. An optional cancellation token for cancelling the sequence at any time. A ValueTask containing the average of the sequence of values. or is . The source sequence is empty. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Computes the average of an async-enumerable sequence of values that are obtained by invoking an asynchronous transform function on each element of the source sequence and awaiting the result.

Counts the elements in an async-enumerable sequence that satisfy a condition.

Type of elements in the source sequence. A sequence of elements to count. An asynchronous predicate to apply to each element in the source sequence. An optional cancellation token for cancelling the sequence at any time. A ValueTask containing the number of elements in the sequence that satisfy the predicate. or is .

Returns the first element of an async-enumerable sequence that satisfies the condition in the predicate.

The type of elements in the sequence. Source async-enumerable sequence. An asynchronous predicate that will be invoked and awaited for each element in the sequence. An optional cancellation token for cancelling the sequence at any time. A ValueTask containing the first element in the sequence that satisfies the predicate. or is . No element satisfies the condition in the predicate. -or- The source sequence is empty.

Returns the first element of an async-enumerable sequence that satisfies the condition in the predicate, or a default value if no element satisfies the condition in the predicate.

The type of element in the sequence. Source async-enumerable sequence. An asynchronous predicate to invoke and await on each element of the sequence. An optional cancellation token for cancelling the sequence at any time. A ValueTask containing the first element in the sequence that satisfies the predicate, or a default value if no element satisfies the predicate. or is .

Invokes an action for each element in the async-enumerable sequence, and returns a Task object that will get signaled when the sequence terminates.

The type of the elements in the source sequence. Source sequence. Action to invoke for each element in the async-enumerable sequence. The optional cancellation token to be used for cancelling the sequence at any time. Task that signals the termination of the sequence. or is null. This operator is especially useful in conjunction with the asynchronous programming features introduced in C# 5.0 and Visual Basic 11.

Invokes an action for each element in the async-enumerable sequence, incorporating the element's index, and returns a Task object that will get signaled when the sequence terminates.

Invokes and awaits an asynchronous action on each element in the source sequence, and returns a task that is signaled when the sequence terminates.

Type of elements in the sequence. Source sequence. Asynchronous action to invoke and await for each element in the source sequence. Optional cancellation token for cancelling the sequence at any time. Task that signals the termination of the sequence. or is .

Invokes and awaits an asynchronous action on each element in the source sequence, incorporating the element's index, and returns a task that is signaled when the sequence terminates.

Type of elements in the sequence. Source sequence. Asynchronous action to invoke and await for each element in the source sequence; the second parameter represents the index of the element. Optional cancellation token for cancelling the sequence at any time. Task that signals the termination of the sequence. or is .

Groups the elements of an async-enumerable sequence according to a specified key selector function.

The type of the elements in the source sequence. The type of the grouping key computed for each element in the source sequence. An async-enumerable sequence whose elements to group. An asynchronous function to extract the key for each element. A sequence of async-enumerable groups, each of which corresponds to a unique key value, containing all elements that share that same key value. or is .

Groups the elements of an async-enumerable sequence according to a specified key selector function and comparer.

The type of the elements in the source sequence. The type of the grouping key computed for each element in the source sequence. An async-enumerable sequence whose elements to group. An asynchronous function to extract the key for each element. An equality comparer to compare keys with. A sequence of async-enumerable groups, each of which corresponds to a unique key value, containing all elements that share that same key value. or or is .

Groups the elements of an async-enumerable sequence and selects the resulting elements by using a specified function.

The type of the elements in the source sequence. The type of the grouping key computed for each element in the source sequence. The type of the elements within the groups computed for each element in the source sequence. An async-enumerable sequence whose elements to group. An asynchronous function to extract the key for each element. An asynchronous function to map each source element to an element in an async-enumerable group. A sequence of async-enumerable groups, each of which corresponds to a unique key value, containing all elements that share that same key value. or or is .

Groups the elements of an async-enumerable sequence and selects the resulting elements by using a specified function.

The type of the elements in the source sequence. The type of the grouping key computed for each element in the source sequence. The type of the elements within the groups computed for each element in the source sequence. An async-enumerable sequence whose elements to group. An asynchronous function to extract the key for each element. An asynchronous function to map each source element to an element in an async-enumerable group. An equality comparer to use to compare keys. A sequence of async-enumerable groups, each of which corresponds to a unique key value, containing all elements that share that same key value. or or or is .

Groups the elements of an async-enumerable sequence according to a specified key selector function, and then applies a result selector function to each group.

Type of element in the source sequence. Type of the grouping key computed for each element in the source sequence. The result type returned by the result selector function. An async-enumerable sequence whose elements to group. An asynchronous function to extract the key for each element. An asynchronous function to transform each group into the result type. An async-enumerable sequence of results obtained by invoking and awaiting the result-selector function on each group. or or is .

Groups the elements of an async-enumerable sequence according to a specified key selector function, and then applies a result selector function to each group.

Type of element in the source sequence. Type of the grouping key computed for each element in the source sequence. The result type returned by the result selector function. An async-enumerable sequence whose elements to group. An asynchronous function to extract the key for each element. An asynchronous function to transform each group into the result type. An equality comparer to use to compare keys. An async-enumerable sequence of results obtained by invoking and awaiting the result-selector function on each group. or or or is .

Groups the elements of an async-enumerable sequence according to a specified key-selector function, applies an element selector to each element of each group, then applies a result selector to each transformed group.

The type of element in the source sequence. The type of the grouping key computed for each element in the source sequence. The type of element computed by the element selector. The type of the final result, computed by applying the result selector to each transformed group of elements. An async-enumerable sequence whose elements to group. An asynchronous function to extract the key for each element. An asynchronous function to apply to each element of each group. An asynchronous function to transform each group into the result type. An async-enumerable sequence of results obtained by invoking the result selector function on each group and awaiting the result. or or or is .

The type of element in the source sequence. The type of the grouping key computed for each element in the source sequence. The type of element computed by the element selector. The type of the final result, computed by applying the result selector to each transformed group of elements. An async-enumerable sequence whose elements to group. An asynchronous function to extract the key for each element. An asynchronous function to apply to each element of each group. An asynchronous function to transform each group into the result type. An equality comparer to use to compare keys. An async-enumerable sequence of results obtained by invoking the result selector function on each group and awaiting the result. or or or or is .

Returns the last element of an async-enumerable sequence that satisfies the condition in the predicate.

The type of the elements in the source sequence. Source async-enumerable sequence. An asynchronous predicate function to evaluate for elements in the source sequence. The optional cancellation token to be used for cancelling the sequence at any time. ValueTask containing the last element in the async-enumerable sequence that satisfies the condition in the predicate. or is null. (Asynchronous) No element satisfies the condition in the predicate. -or- The source sequence is empty.

Returns the last element of an async-enumerable sequence that satisfies the condition in the predicate, or a default value if no such element exists.

The type of the elements in the source sequence. Source async-enumerable sequence. An asynchronous predicate function to evaluate for elements in the source sequence. The optional cancellation token to be used for cancelling the sequence at any time. ValueTask containing the last element in the async-enumerable sequence that satisfies the condition in the predicate, or a default value if no such element exists. or is null.

Returns an async-enumerable sequence containing a that represents the number of elements in the specified async-enumerable sequence that satisfy a condition.

The type of the elements in the source sequence. An async-enumerable sequence that contains elements to be counted. An asynchronous predicate to test each element for a condition. The optional cancellation token to be used for cancelling the sequence at any time. An async-enumerable sequence containing a single element with a number that represents how many elements in the input sequence satisfy the condition in the predicate function. or is null. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Invokes a transform function on each element of a sequence and returns the maximum value.

The type of the elements in the source sequence. The type of the objects derived from the elements in the source sequence to determine the maximum of. An async-enumerable sequence to determine the minimum element of. A transform function to apply to each element. The optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing a single element with the value that corresponds to the maximum element in the source sequence. or is null. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Invokes and awaits a transform function on each element of a sequence and returns the maximum value.

The type of the elements in the source sequence. The type of the objects derived from the elements in the source sequence to determine the maximum of. An async-enumerable sequence to determine the minimum element of. An asynchronous transform function to invoke and await on each element. The optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing a single element with the value that corresponds to the maximum element in the source sequence. or is null. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Invokes a transform function on each element of a sequence and returns the minimum value.

The type of the elements in the source sequence. The type of the objects derived from the elements in the source sequence to determine the minimum of. An async-enumerable sequence to determine the minimum element of. A transform function to apply to each element. The optional cancellation token to be used for cancelling the sequence at any time. A ValueTask sequence containing a single element with the value that corresponds to the minimum element in the source sequence. or is null. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Invokes and awaits a transform function on each element of a sequence and returns the minimum value.

The type of the elements in the source sequence. The type of the objects derived from the elements in the source sequence to determine the minimum of. An async-enumerable sequence to determine the minimum element of. An asynchronous transform function to invoke and await on each element. The optional cancellation token to be used for cancelling the sequence at any time. A ValueTask sequence containing a single element with the value that corresponds to the minimum element in the source sequence. or is null. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Invokes and awaits a transform function on each element of a sequence and returns the maximum value.

Type of elements in the source sequence. The source sequence. An asynchronous transform function to invoke and await on each element of the source. The optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing the maximum value in the sequence. or is .

Invokes and awaits a transform function on each element of a sequence and returns the maximum value.

Sorts the elements of a sequence in ascending order according to a key obtained by invoking a transform function on each element and awaiting the result.

The type of the elements of source. The type of the key returned by keySelector. An async-enumerable sequence of values to order. An asynchronous function to extract a key from an element. An ordered async-enumerable sequence whose elements are sorted according to a key. or is null.

Sorts the elements of a sequence in ascending order by using a specified comparer. The keys are obtained by invoking the transform function on each element and awaiting the result.

The type of the elements of source. The type of the key returned by keySelector. An async-enumerable sequence of values to order. An asynchronous function to extract a key from an element. A comparer to compare keys. An ordered async-enumerable sequence whose elements are sorted according to a key. or is null.

Sorts the elements of a sequence in descending order according to a key obtained by invoking a transform function on each element and awaiting the result.

Sorts the elements of a sequence in descending order by using a specified comparer. The keys are obtained by invoking the transform function on each element and awaiting the result.

The type of the elements of source. The type of the key returned by keySelector. An async-enumerable sequence of values to order. An asynchronous function to extract a key from an element. A comparer to compare keys. An ordered async-enumerable sequence whose elements are sorted in descending order according to a key. or is null.

Performs a subsequent ordering of the elements in a sequence in ascending order according to a key obtained by invoking a transform function on each element and awaiting the result.

The type of the elements of source. The type of the key returned by keySelector. An ordered async-enumerable sequence that contains elements to sort. An asynchronous function to extract a key from each element. An ordered async-enumerable whose elements are sorted according to a key. or is null.

Performs a subsequent ordering of the elements in a sequence in ascending order by using a specified comparer. The keys are obtained by invoking a transform function on each element and awaiting the result.

The type of the elements of source. The type of the key returned by keySelector. An ordered async-enumerable sequence that contains elements to sort. An asynchronous function to extract a key from each element. A comparer to compare keys. An ordered async-enumerable whose elements are sorted according to a key. or is null.

Performs a subsequent ordering of the elements in a sequence in descending order, according to a key obtained by invoking a transform function on each element and awaiting the result.

The type of the elements of source. The type of the key returned by keySelector. An ordered async-enumerable sequence that contains elements to sort. An asynchronous function to extract a key from each element. An ordered async-enumerable sequence whose elements are sorted in descending order according to a key. or is null.

Performs a subsequent ordering of the elements in a sequence in descending order by using a specified comparer. The keys are obtained by invoking a transform function on each element and awaiting the result.

The type of the elements of source. The type of the key returned by keySelector. An ordered async-enumerable sequence that contains elements to sort. An asynchronous function to extract a key from each element. A comparer to compare keys. An ordered async-enumerable sequence whose elements are sorted in descending order according to a key. or is null.

Projects each element of an async-enumerable sequence into a new form by applying an asynchronous selector function to each member of the source sequence and awaiting the result.

The type of the elements in the source sequence. The type of the elements in the result sequence, obtained by running the selector function for each element in the source sequence and awaiting the result. A sequence of elements to invoke a transform function on. An asynchronous transform function to apply to each source element. An async-enumerable sequence whose elements are the result of invoking the transform function on each element of the source sequence and awaiting the result. or is null.

Projects each element of an async-enumerable sequence into a new form by applying an asynchronous selector function that incorporates each element's index to each element of the source sequence and awaiting the result.

The type of elements in the source sequence. The type of elements in the result sequence, obtained by running the selector function for each element and its index, and awaiting the result. A sequence of elements to invoke a transform function on. An asynchronous transform function to apply to each source element; the second parameter represents the index of the element. An async-enumerable sequence whose elements are the result of invoking the transform function on each element and its index of the source sequence and awaiting the result. or is null.

Projects each element of an async-enumerable sequence into an async-enumerable sequence and merges the resulting async-enumerable sequences into one async-enumerable sequence.

The type of elements in the source sequence. The type of elements in the projected inner sequences and the merged result sequence. An async-enumerable sequence of elements to project. An asynchronous selector function to apply to each element of the source sequence. An async-enumerable sequence whose elements are the result of invoking the one-to-many transform function on each element of the source sequence and awaiting the result. or is null.

Projects each element of an async-enumerable sequence into an async-enumerable sequence by incorporating the element's index and merges the resulting async-enumerable sequences into an async-enumerable sequence.

The type of elements in the source sequence. The type of elements in the projected inner sequences and the merged result sequence. An async-enumerable sequence of elements to project. An asynchronous selector function to apply to each element; the second parameter represents the index of the element. An async-enumerable sequence who's elements are the result of invoking the one-to-many transform function on each element of the source sequence and awaiting the result. or is null.

Projects each element of an async-enumerable sequence to an async-enumerable sequence by awaiting the result of a transform function, invokes the result selector for each of the source elements and each of the corrasponding inner-sequence's elements and awaits the result, and merges the results into one async-enumerable sequence.

The type of elements in the source sequence. The type of elements in the projected intermediate sequences. The type of elements in the result sequence. An async-enumerable sequence of elements to project. An asynchronous transform function to apply to each source element. An asynchronous transform function to apply to each element of the intermediate sequence. An async-enumerable sequence whose elements are the result of invoking the one-to-many transform function on each element of the input sequence, awaiting the result, applying to each element of the intermediate sequences along with their corrasponding source element and awaiting the result. , , or is .

Projects each element of an async-enumerable sequence to an async-enumerable sequence by awaiting the result of a transform function that incorporates each element's index, invokes the result selector for the source element and each of the corrasponding inner-sequence's elements and awaits the result, and merges the results into one async-enumerable sequence.

The type of elements in the source sequence. The type of elements in the projected intermediate sequences. The type of elements in the result sequence. An async-enumerable sequence of elements to project. An asynchronous transform function to apply to each source element; the second parameter represents the index of the element. An asynchronous transform function to apply to each element of the intermediate sequence. An async-enumerable sequence whose elements are the result of invoking the one-to-many transform function on each element of the input sequence, awaiting the result, applying to each element of the intermediate sequences olong with their corrasponding source element and awaiting the result. , , or is .

Returns the only element of an async-enumerable sequence that satisfies the condition in the asynchronous predicate, and reports an exception if there is not exactly one element in the async-enumerable sequence that matches the predicate.

The type of elements in the source sequence. Source async-enumerable sequence. An asynchronous predicate that will be applied to each element of the source sequence. The optional cancellation token to be used for cancelling the sequence at any time. ValueTask containing the only element in the async-enumerable sequence that satisfies the condition in the asynchronous predicate. or is null. (Asynchronous) No element satisfies the condition in the predicate. -or- More than one element satisfies the condition in the predicate. -or- The source sequence is empty.

Returns the only element of an async-enumerable sequence that satisfies the condition in the asynchronous predicate, or a default value if no such element exists, and reports an exception if there is more than one element in the async-enumerable sequence that matches the predicate.

The type of elements in the source sequence. Source async-enumerable sequence. An asynchronous predicate that will be applied to each element of the source sequence. The optional cancellation token to be used for cancelling the sequence at any time. ValueTask containing the only element in the async-enumerable sequence that satisfies the condition in the asynchronous predicate, or a default value if no such element exists. or is null. (Asynchronous) More than one element satisfies the condition in the predicate.

Bypasses elements in an async-enumerable sequence as long as a condition is true, and then returns the remaining elements.

The type of elements in the source sequence. An async-enumerable sequence to return elements from. An asynchronous function to test each element for a condition. An async-enumerable sequence containing the elements in the source sequence starting at the first element that does not pass the test specified by the predicate. or is .

Bypasses elements in an async-enumerable sequence as long as a condition is true, and then returns the remaining elements. The index of the element is used by the predicate.

The type of elements in the source sequence. An async-enumerable sequence to return elements from. An asynchronous function to test each element for a condition; the second parameter of the function represents the index of the element. An async-enumerable sequence containing the elements in the source sequence starting at the first element that does not pass the test specified by the predicate. or is .

Returns elements from an async-enumerable sequence as long as a specified condition is true.

The type of the elements in the source sequence. A sequence to return elements from. An asynchronous predicate to test each element for a condition. An async-enumerable sequence that contains the elements from the input sequence that occur before the element at which the test no longer passes. or is null.

Returns elements from an async-enumerable sequence as long as a specified condition is true. The element's index is used in the logic of the predicate function.

The type of the elements in the source sequence. A sequence to return elements from. An asynchronous function to test each element for a condition; the second parameter of the function represents the index of the source element. An async-enumerable sequence that contains the elements from the input sequence that occur before the element at which the test no longer passes. or is null.

Creates a dictionary from an async-enumerable sequence by invoking a key-selector function on each element and awaiting the result.

The type of the elements in the source sequence. The type of the dictionary key computed for each element in the source sequence. An async-enumerable sequence to create a dictionary for. An asynchronous function to extract a key from each element. The optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing a dictionary mapping unique key values onto the corresponding source sequence's element. or is null. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Creates a dictionary from an async-enumerable sequence by invoking a key-selector function on each element and awaiting the result.

The type of the elements in the source sequence. The type of the dictionary key computed for each element in the source sequence. An async-enumerable sequence to create a dictionary for. An asynchronous function to extract a key from each element. An equality comparer to compare keys. The optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing a dictionary mapping unique key values onto the corresponding source sequence's element. or or is null. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Creates a dictionary from an async-enumerable sequence using the specified asynchronous key and element selector functions.

The type of the elements in the source sequence. The type of the dictionary key computed for each element in the source sequence. The type of the dictionary value computed for each element in the source sequence. An async-enumerable sequence to create a dictionary for. An asynchronous function to extract a key from each element. An asynchronous transform function to produce a result element value from each element. The optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing a dictionary mapping unique key values onto the corresponding source sequence's element. or or is null. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Creates a dictionary from an async-enumerable sequence using the specified asynchronous key and element selector functions.

The type of the elements in the source sequence. The type of the dictionary key computed for each element in the source sequence. The type of the dictionary value computed for each element in the source sequence. An async-enumerable sequence to create a dictionary for. An asynchronous function to extract a key from each element. An asynchronous transform function to produce a result element value from each element. An equality comparer to compare keys. The optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing a dictionary mapping unique key values onto the corresponding source sequence's element. or or or is null. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Converts an async-enumerable sequence to an enumerable sequence.

The type of the elements in the source sequence. An async-enumerable sequence to convert to an enumerable sequence. The enumerable sequence containing the elements in the async-enumerable sequence. is null.

Creates a lookup from an async-enumerable sequence by invoking a key-selector function on each element and awaiting the result.

The type of the elements in the source sequence. The type of the lookup key computed for each element in the source sequence. An async-enumerable sequence to create a lookup for. An asynchronous function to extract a key from each element. The optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing a lookup mapping unique key values onto the corresponding source sequence's elements. or is null. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Creates a lookup from an async-enumerable sequence by invoking a key-selector function on each element and awaiting the result.

The type of the elements in the source sequence. The type of the lookup key computed for each element in the source sequence. An async-enumerable sequence to create a lookup for. An asynchronous function to extract a key from each element. An equality comparer to compare keys. The optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing a lookup mapping unique key values onto the corresponding source sequence's elements. or or is null. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Creates a lookup from an async-enumerable sequence by invoking key and element selector functions on each source element and awaiting the results.

The type of the elements in the source sequence. The type of the lookup key computed for each element in the source sequence. The type of the lookup value computed for each element in the source sequence. An async-enumerable sequence to create a lookup for. An asynchronous function to extract a key from each element. An asynchronous transform function to produce a result element value from each element. The optional cancellation token to be used for cancelling the sequence at any time. An async-enumerable sequence containing a single element with a lookup mapping unique key values onto the corresponding source sequence's elements. or or is null. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Creates a lookup from an async-enumerable sequence by invoking key and element selector functions on each source element and awaiting the results.

The type of the elements in the source sequence. The type of the lookup key computed for each element in the source sequence. The type of the lookup value computed for each element in the source sequence. An async-enumerable sequence to create a lookup for. An asynchronous function to extract a key from each element. An asynchronous transform function to produce a result element value from each source element. An equality comparer to compare keys. The optional cancellation token to be used for cancelling the sequence at any time. A ValueTask containing a lookup mapping unique key values onto the corresponding source sequence's elements. or or or is null. The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.

Filters the elements of an async-enumerable sequence based on an asynchronous predicate.

The type of the elements in the source sequence. An async-enumerable sequence whose elements to filter. An asynchronous predicate to test each source element for a condition. An async-enumerable sequence that contains elements from the input sequence that satisfy the condition. or is null.

Filters the elements of an async-enumerable sequence based on an asynchronous predicate that incorporates the element's index.

The type of the elements in the source sequence. An async-enumerable sequence whose elements to filter. An asynchronous predicate to test each source element for a condition; the second parameter of the function represents the index of the source element. An async-enumerable sequence that contains elements from the input sequence that satisfy the condition. or is null.

Merges two async-enumerable sequences into one async-enumerable sequence by combining their elements in a pairwise fashion.

The type of the elements in the first source sequence. The type of the elements in the second source sequence. The type of the elements in the result sequence, returned by the selector function. First async-enumerable source. Second async-enumerable source. An asynchronous function to invoke and await for each consecutive pair of elements from the first and second source. An async-enumerable sequence containing the result of pairwise combining the elements of the first and second source using the specified result selector function. or or is null.