using System; using System.Collections.Generic; using System.Linq; static class Test { public static IEnumerable<T> Select<T> (this Array This, Func<object, T> transform) { foreach (var item in This) { yield return transform (item); } } public static void Main () { Type type = typeof (int); IEnumerable<string> properties = new[] { "x" }; var checkIncludeExists = from n in properties let p = type.GetProperty (n) where p == null select n; foreach (var item in checkIncludeExists) { } } }