C# compiler

CodeDom.Compiler

using System;

namespace Sample
{
    class Test
    {
        public static System.Reflection.Assembly Compile(string source)
        {
            var p = new Microsoft.CSharp.CSharpCodeProvider();
            var c = p.CreateCompiler();
            var parameters = new System.CodeDom.Compiler.CompilerParameters();

            parameters.GenerateExecutable = false;

            var r = c.CompileAssemblyFromSource(parameters, string.Format(
                "using System; namespace Foo {{ public static class MethodStub {{ public static void foo() {{ {0} }} }} }}", 
                source));

            return r.CompiledAssembly;
        }

        public static void Call(System.Reflection.Assembly a, string method)
        {
            var t = a.GetType("Foo.MethodStub");

            t.InvokeMember(method,
                System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Static | System.Reflection.BindingFlags.InvokeMethod,
                System.Type.DefaultBinder, null, null);
        }

        [STAThread]
        static void Main(string[] args)
        {
            var a1 = Compile("Console.WriteLine(\"Hello, Earth\");");
            var a2 = Compile("Console.WriteLine(\"Hello, Moon\");");

            Call(a2, "foo");
            Call(a1, "foo");

            System.Console.ReadKey(true);
        }
    }
}

        var p1 = Expression.Parameter(typeof(int));
        var c1 = Expression.Constant(13);
        var add = Expression.Add(p1, c1);

        var lambda = Expression.Lambda(add, p1);

        var d = lambda.Compile();

        Console.WriteLine(d.DynamicInvoke(10));