Transform

Transform

Transforming data from input stream

Map

Nuances with return result types

Type is

typealias returnedType: Publishers
.Map<AnyPublisher<URL, Never>, Playable>?

 let results = urlOrchestrator?
            .output
            .resolvedURL
            .map { Playable(url: $0)}

// Compiler warning

Cannot convert value of type 'URL' to expected argument type 'Published<URL>.Publisher

So xcode - swift llvm compiler has hard time figuring out the return type from the .map closure since it could be upstream .resolvedURL Published<URL> or just Publisher.output: URL.

So you could get away with manually capturing value to give compiler more context. After doing this you can resort back to it since the compiler would have deduce its type automatically in its compiler cache? Don't know if it fails again if someone clones this again on a different machine. Maybe it makes the best guess at that time to either use this or that.

// 1st approach
.map { value in
   NitroPlayable(url: value)
}

// 2nd approach
.map( { Playable(url: $0)} )

If we do type erasure on Publisher
eraseToAnyPublisher

typealias returnedType: AnyPublisher<Playable, Never>?

let results: returnedType = urlOrchestrator?
            .output
            .resolvedURL
            .map( { Playable(url: $0)} )
            .eraseToAnyPublisher()