---
title: LazySequence
framework: swift
role: symbol
role_heading: Structure
path: swift/lazysequence
---

# LazySequence

A sequence containing the same elements as a Base sequence, but on which some operations such as map and filter are implemented lazily.

## Declaration

```swift
@frozen struct LazySequence<Base> where Base : Sequence
```

## Overview

Overview See also: LazySequenceProtocol

## Topics

### Instance Methods

- [mapAnnotations(_:)](swift/lazysequence/mapannotations(_:).md)
- [mapFeatures(_:)](swift/lazysequence/mapfeatures(_:).md)

### Default Implementations

- [BidirectionalCollection Implementations](swift/lazysequence/bidirectionalcollection-implementations.md)
- [Collection Implementations](swift/lazysequence/collection-implementations.md)
- [LazySequenceProtocol Implementations](swift/lazysequence/lazysequenceprotocol-implementations.md)
- [RandomAccessCollection Implementations](swift/lazysequence/randomaccesscollection-implementations.md)
- [Sequence Implementations](swift/lazysequence/sequence-implementations.md)

## Relationships

### Conforms To

- [BidirectionalCollection](swift/bidirectionalcollection.md)
- [Collection](swift/collection.md)
- [Copyable](swift/copyable.md)
- [Escapable](swift/escapable.md)
- [LazyCollectionProtocol](swift/lazycollectionprotocol.md)
- [LazySequenceProtocol](swift/lazysequenceprotocol.md)
- [RandomAccessCollection](swift/randomaccesscollection.md)
- [Sendable](swift/sendable.md)
- [SendableMetatype](swift/sendablemetatype.md)
- [Sequence](swift/sequence.md)

## See Also

### Lazy Wrappers

- [LazyMapSequence](swift/lazymapsequence.md)
- [LazyFilterSequence](swift/lazyfiltersequence.md)
- [LazyPrefixWhileSequence](swift/lazyprefixwhilesequence.md)
- [LazyDropWhileSequence](swift/lazydropwhilesequence.md)
- [LazyCollection](swift/lazycollection.md)
- [LazyDropWhileCollection](swift/lazydropwhilecollection.md)
- [LazyFilterCollection](swift/lazyfiltercollection.md)
- [LazyMapCollection](swift/lazymapcollection.md)
- [LazyPrefixWhileCollection](swift/lazyprefixwhilecollection.md)