Binding’s affordances.

binding-exploration.swift

import SwiftUI

extension Binding {
	func zip(
		_ other: Binding<Value>
	) -> Binding<(Value, Value)> {
		Binding<(Value, Value)>(
			get: { (self.wrappedValue, other.wrappedValue) },
			set: { pair in
				self.wrappedValue = pair.0
				other.wrappedValue = pair.1
			}
		)
	}
}

func join<Value>(nested: Binding<Binding<Value>>) -> Binding<Value> {
	Binding<Value>(
		get: { nested.wrappedValue.wrappedValue },
		set: { nested.wrappedValue.wrappedValue = $0 }
	)
}

extension Binding {
	func flatMap<TransformedValue>(
		_ transform: WritableKeyPath<Value, Binding<TransformedValue>>
	) -> Binding<TransformedValue> {
		Binding<TransformedValue>(
			get: { self.wrappedValue[keyPath: transform].wrappedValue },
			set: { self.wrappedValue[keyPath: transform].wrappedValue = $0 }
		)
	}
}