//Binds symbols of the given string to the given body.
public void DefineSymbol(string name, Expression body)
{
Evaluate(Expression.NewDefine(name, body));
//frozenEnv.Value = frozenEnv.Value.Add(name, env.Lookup(name));
}
//Binds symbols of the given string to the given External Function.
public void DefineExternal(string name, FSharpFunc <FSharpList <Value>, Value> func)
{
//add(name, Value.NewFunction(func));
Evaluate(Expression.NewDefine(name, Expression.NewFunction_E(func)));
}