Let with Linq节省了双枚举而不是使用扩展方法样式

第一个查询将更频繁地枚举由于双。select()和let操作符消除真正的双枚举吗?

var y = product.Documents
.Where(p => p.Type == "test_DOC")
.Select(p => GetPathToLabel(p.Name))
.Select(path => FileExists(path) ? File.ReadAllBytes(path) : null)
.Where(data => data != null)
.ToList();
var x = (from p in product.Documents
     where p.Type == "test_DOC"
     let path = GetPathToLabel(p.Name)
     let data = FileExists(path) ? File.ReadAllBytes(path) : null
     where data != null
     select data).ToList();