maybe.cs

public static class ExpressionsEx
{
    public static string PropertyName<TSource, TResult>(Expression<Func<TSource, TResult>> expression)
    {
        if (expression == null)
        {
            throw new ArgumentNullException("expression");
        }

        if (!(expression.Body is MemberExpression))
        {
            throw new ArgumentException("Property access exxpressions are supported only");
        }

        var member = ((MemberExpression) expression.Body).Member;
        if (!(member is PropertyInfo))
        {
            throw new ArgumentException("Property access exxpressions are supported only");
        }

        return member.Name;
    }

    public static string PropertyName2<TSource, TResult>(Expression<Func<TSource, TResult>> expression)
    {
        return expression
            .EnsureIsNotNull(() => new ArgumentNullException("expression"))
            .Maybe(e => e.Body as MemberExpression)
            .Maybe(m => m.Member as PropertyInfo)
            .EnsureIsNotNull(() => new ArgumentException("Property access exxpressions are supported only"))
            .Maybe(p => p.Name);
    }
}