Moving extensions around

main/Extensions/Equatable.swift

@@ -0,0 +1,33 @@
+
+precedencegroup CompareAssignPrecedence {
+	assignment: true
+	associativity: left
+	higherThan: ComparisonPrecedence
+}
+
+infix operator <-? : CompareAssignPrecedence
+infix operator <-/ : CompareAssignPrecedence
+
+extension Equatable {
+	/// Assign a new value to `lhs` if `newValue` differs from the previous value. Return `false` if they are equal.
+	/// - Returns: `true` if `lhs` was overwritten with another value
+	static func <-?(lhs: inout Self, newValue: Self) -> Bool {
+		if lhs != newValue {
+			lhs = newValue
+			return true
+		}
+		return false
+	}
+	
+	/// Assign a new value to `lhs` if `newValue` differs from the previous value.
+	/// Return tuple with both values. Or `nil` if they are equal.
+	/// - Returns: `nil` if `previousValue == newValue`
+	static func <-/(lhs: inout Self, newValue: Self) -> (previousValue: Self, newValue: Self)? {
+		let previousValue = lhs
+		if previousValue != newValue {
+			lhs = newValue
+			return (previousValue, newValue)
+		}
+		return nil
+	}
+}