DotNext by Roman Sakno

<PackageReference Include="DotNext" Version="1.2.4" />

.NET API 245,248 bytes

 Collection

public static class Collection
Provides utility methods to work with collections.
public static void AddAll<T>(this ICollection<T> collection, IEnumerable<T> items)

Adds multiple items into collection.

public static ReadOnlyCollectionView<I, O> Convert<I, O>(this IReadOnlyCollection<I> collection, ref ValueFunc converter)

Returns lazily converted read-only collection.

public static ReadOnlyCollectionView<I, O> Convert<I, O>(this IReadOnlyCollection<I> collection, Converter<I, O> converter)

Returns lazily converted read-only collection.

public static T[] ToArray<T>(ICollection<T> collection)

Converts collection into single-dimensional array.

public static T[] ToArray<T>(IReadOnlyCollection<T> collection)

Converts read-only collection into single-dimensional array.