runes-test.swift

import Foundation
import Runes

struct Recipe {
    let imageURLString: String?
}
let recipe = Recipe(imageURLString: "http://hoge/image.png")

// default
if let imageURLString = recipe.imageURLString, let imageURL = URL(string: imageURLString) {
    print(imageURL)
}

// with Runes
if let imageURL = recipe.imageURLString >>- { URL(string: $0) } {
    print(imageURL)
}