How to convert a query to lambda based

var usersWithRoles = (from user in context.Users
                                  select new
                                  {
                                      UserId = user.Id,
                                      Username = user.UserName,
                                      Email = user.Email,
                                      RoleNames = (from userRole in user.Roles
                                                   join role in context.Roles on userRole.RoleId
                                                   equals role.Id
                                                   select role.Name).ToList()
                                  }).ToList().Select(p => new Users_in_Role_ViewModel()

                                  {
                                      UserId = p.UserId,
                                      Username = p.Username,
                                      Email = p.Email,
                                      Role = string.Join(",", p.RoleNames)
                                  });  

guide me how could i compose the above query using lambda if possible. thanks