Combine A custom publisher

Publisher+isPrimeInteger.swift

import Foundation
import Combine

extension Publisher{
    
    func isPrimeInteger<T: BinaryInteger>() -> Publishers
        .CompactMap<Self, T> where Output == T {
            compactMap{self.isPrime($0)}
    }
    
    
    func isPrime<T: BinaryInteger>(_ n: T) -> T? {
        guard n != 2 else { return n }
        guard n % 2 != 0 && n > 1 else { return nil }

        var i = 3
        while i * i <= n {
            if (Int(n) % i) == 0 {
                return nil
            }
            i += 2
        }

        return n
    }
}

let numbers:[Int] = [1, 2, 3, 4, 5, 6, 7, 8, 9]
numbers
    .publisher
    .isPrimeInteger()
    .sink { print($0) }