System.Collections.Immutable by Microsoft

<PackageReference Include="System.Collections.Immutable" Version="8.0.0-preview.5.23280.8" />

.NET API 253,616 bytes

IReadOnlySet<T>

interface IReadOnlySet<T> : IReadOnlyCollection<T>, IEnumerable<T>, IEnumerable

bool Contains(T item)

bool IsProperSubsetOf(IEnumerable<T> other)

bool IsProperSupersetOf(IEnumerable<T> other)

bool IsSubsetOf(IEnumerable<T> other)

bool IsSupersetOf(IEnumerable<T> other)

bool Overlaps(IEnumerable<T> other)

bool SetEquals(IEnumerable<T> other)