REPL_CSharp.cs

using System;
using Roslyn.Compilers;
using Roslyn.Scripting.CSharp;
using Roslyn.Scripting;

namespace Roslyn_CTP2012
{
    static class Program
    {
        static void Main(string[] args)
        {
            Action<object> print = Console.WriteLine;

            var session = CreateSession();

            print("Roslyn REPL for C#");

            while (true)
            {
                Console.Write(">");
                try
                {
                    print(session.Execute(Console.ReadLine()));
                }
                catch (Exception e)
                {
                    print(e);
                }
            }
        }

        static Session CreateSession()
        {
            return new ScriptEngine()
                .CreateSession()
                .AddAssemblyReference("System")
                .AddAssemblyReference("System.Core")
                .AddAssemblyReference("System.Data")
                .AddAssemblyReference("System.Data.DataSetExtensions");
        }

        static Session AddAssemblyReference(
            this Session session,
            string assemblyName
            )
        {
            var reference = MetadataReference
                .CreateAssemblyReference(assemblyName);

            session
                .AddReference(reference);

            return session;
        }
    }
}