Created Failable[keyPath:] subscript

Sources/Validation/Failable.swift

@@ -35,6 +35,13 @@ public struct Failable<T, Validations> where Validations: Validation, Validation
         try self <~ t
     }
     
+    /// Gets the value of a property of the `value` property using a key path.
+    ///
+    /// - Parameter path: The key path of the property to get from the `value` property.
+    public subscript<Value>(keyPath path: KeyPath<T, Value>) -> Value {
+        return self.value[keyPath: path]
+    }
+    
     internal func validate(_ value: T)throws {
         try Validations.validate(value)
         try Validations.safeSubvalidations.forEach { validation in try validation.validate(value) }