ScriptReferences.cs

ScriptOptions scriptOptions = ScriptOptions.Default;

//Add reference to mscorlib
var mscorlib = typeof(System.Object).Assembly;
var systemCore = typeof(System.Linq.Enumerable).Assembly;
scriptOptions = scriptOptions.AddReferences(mscorlib, systemCore);
//Add namespaces
scriptOptions = scriptOptions.AddNamespaces("System");
scriptOptions = scriptOptions.AddNamespaces("System.Linq");
scriptOptions = scriptOptions.AddNamespaces("System.Collections.Generic");

var state = await CSharpScript.RunAsync(@"var x = new List(){1,2,3,4,5};", scriptOptions);
state = await state.ContinueWithAsync("var y = x.Take(3).ToList();");

var y = state.Variables["y"];
var yList = (List)y.Value;
foreach(var val in yList)
{
  Console.Write(val + " "); // Prints 1 2 3
}