primary associated types

import Combine

//SE-361 Extensions on bound generic types (also 244 & 346)
extension Publisher<Int, Never> {
    func make(byAppending value: Output) -> some Publisher<Output, Failure> {
        append(value)
    }
}
let p = [0].publisher.make(byAppending: 1)

//SE-244 Opaque Result Types
func makeIntPublisher<Value>(value: Value) -> some Publisher<Value, Never> {
    CurrentValueSubject<Value, Never>(value)
}

//SE-346 Lightweight same-type requirements for primary associated types
//SE-335 Existential any
let publishers: [any Publisher<Int, Never>] = [
    p,
    Just(2),
    makeIntPublisher(value: 3)
]

//SE-328 Structural opaque result types
//SE-352 Implicitly Opened Existentials
func printValues(for publisher: some Publisher<some CustomStringConvertible, Never>) -> AnyCancellable {
    publisher.sink { print($0) }
}

var subscriptions: Set<AnyCancellable> = []
for publisher in publishers {
    printValues(for: publisher).store(in: &subscriptions)
}