---
title: Publishers.Merge4
framework: combine
role: symbol
role_heading: Structure
path: combine/publishers/merge4
---

# Publishers.Merge4

A publisher created by applying the merge function to four upstream publishers.

## Declaration

```swift
struct Merge4<A, B, C, D> where A : Publisher, B : Publisher, C : Publisher, D : Publisher, A.Failure == B.Failure, A.Output == B.Output, B.Failure == C.Failure, B.Output == C.Output, C.Failure == D.Failure, C.Output == D.Output
```

## Topics

### Creating a merge-four publisher

- [init(_:_:_:_:)](combine/publishers/merge4/init(_:_:_:_:).md)

### Merging elements

- [merge(with:)](combine/publishers/merge4/merge(with:).md)
- [merge(with:_:)](combine/publishers/merge4/merge(with:_:).md)
- [merge(with:_:_:)](combine/publishers/merge4/merge(with:_:_:).md)
- [merge(with:_:_:_:)](combine/publishers/merge4/merge(with:_:_:_:).md)

### Declaring supporting types

- [Publishers.Merge4.Output](combine/publishers/merge4/output.md)
- [Publishers.Merge4.Failure](combine/publishers/merge4/failure.md)

### Inspecting publisher properties

- [a](combine/publishers/merge4/a.md)
- [b](combine/publishers/merge4/b.md)
- [c](combine/publishers/merge4/c.md)
- [d](combine/publishers/merge4/d.md)

### Comparing publishers

- [==(_:_:)](combine/publishers/merge4/==(_:_:).md)

### Default Implementations

- [Equatable Implementations](combine/publishers/merge4/equatable-implementations.md)

## Relationships

### Conforms To

- [Equatable](swift/equatable.md)
- [Publisher](combine/publisher.md)

## See Also

### Combining elements from multiple publishers

- [Publishers.CombineLatest](combine/publishers/combinelatest.md)
- [Publishers.CombineLatest3](combine/publishers/combinelatest3.md)
- [Publishers.CombineLatest4](combine/publishers/combinelatest4.md)
- [Publishers.Merge](combine/publishers/merge.md)
- [Publishers.Merge3](combine/publishers/merge3.md)
- [Publishers.Merge5](combine/publishers/merge5.md)
- [Publishers.Merge6](combine/publishers/merge6.md)
- [Publishers.Merge7](combine/publishers/merge7.md)
- [Publishers.Merge8](combine/publishers/merge8.md)
- [Publishers.MergeMany](combine/publishers/mergemany.md)
- [Publishers.Zip](combine/publishers/zip.md)
- [Publishers.Zip3](combine/publishers/zip3.md)
- [Publishers.Zip4](combine/publishers/zip4.md)