using System;

using System.Reflection;

using System.Collections.Generic;

using System.Linq;

using System.Linq.Expressions;

​

public class Program

{

    public static void Main()

    {

        // find the Enumerable.Where with 2 parameters using reflection

        var where = typeof(Enumerable).GetMethods(BindingFlags.Public | BindingFlags.Static)

            .First(mi => mi.Name == "Where" && mi.GetParameters().Length == 2);

​

        // make generic Enumerable.Where<Item>

        var whereItem = where.MakeGenericMethod(typeof(Item));

        // sample data 

        IList<Item> items = new List<Item>

        {

            new Item

            {

                I = 1

            },

            new Item

            {

                I = 2

            }

        };

        // sample filter

        Func<Item, bool> filter = i => i.I > 1;

        // create expression

        var expr = Expression.Call(whereItem, Expression.Constant(items), Expression.Constant(filter));

        // validate

        var enumerable = Expression.Lambda<Func<IEnumerable<Item>>>(expr).Compile()();

        Console.WriteLine(enumerable.Count());

    }

}

​

public class Item

{

    public int I { get; set; }

}