if(Cache::has('user_'. $id)){
    return Cache::get('user_'. $id);
}
$user = User::where('id', $id)->first();
Cache::put('user_'. $id, $user, $minute);
return $user;

你现在可以这样写

return Cache::remeber('user_'. $id, $minute, function($id) {
    return User::where('id', $id)->first();
});