# LazySequenceProtocol Implementations ## Topics ### Instance Properties [`var elements: LazySequence.Elements`](/documentation/Swift/LazySequence/elements-swift.property) The `Base` (presumably non-lazy) sequence from which `self` was created. [`var lazy: LazySequence`](/documentation/Swift/LazySequence/lazy) ### Instance Methods [`func compactMap((Self.Elements.Element) -> ElementOfResult?) -> LazyMapSequence>, ElementOfResult>`](/documentation/Swift/LazySequence/compactMap(_:)-73i9g) Returns the non-`nil` results of mapping the given transformation over this sequence. [`func drop(while: (Self.Elements.Element) -> Bool) -> LazyDropWhileSequence`](/documentation/Swift/LazySequence/drop(while:)) Returns a lazy sequence that skips any initial elements that satisfy `predicate`. [`func filter((Self.Elements.Element) -> Bool) -> LazyFilterSequence`](/documentation/Swift/LazySequence/filter(_:)) Returns the elements of `self` that satisfy `isIncluded`. [`func flatMap((Self.Elements.Element) -> ElementOfResult?) -> LazyMapSequence>, ElementOfResult>`](/documentation/Swift/LazySequence/flatMap(_:)-102bh) Returns the non-`nil` results of mapping the given transformation over this sequence. [`func flatMap((Self.Elements.Element) -> SegmentOfResult) -> LazySequence>>`](/documentation/Swift/LazySequence/flatMap(_:)-7fl2l) Returns the concatenated results of mapping the given transformation over this sequence. [`func joined() -> LazySequence>`](/documentation/Swift/LazySequence/joined()-2zoe4) Returns a lazy sequence that concatenates the elements of this sequence of sequences. [`func map((Self.Element) -> U) -> LazyMapSequence`](/documentation/Swift/LazySequence/map(_:)-5eh3s) Returns a `LazyMapSequence` over this `Sequence`. The elements of the result are computed lazily, each time they are read, by calling `transform` function on a base element. [`func prefix(while: (Self.Elements.Element) -> Bool) -> LazyPrefixWhileSequence`](/documentation/Swift/LazySequence/prefix(while:)) Returns a lazy sequence of the initial consecutive elements that satisfy `predicate`. ### Type Aliases [`typealias Elements`](/documentation/Swift/LazySequence/Elements-swift.typealias) A `Sequence` that can contain the same elements as this one, possibly with a simpler type. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)