我有两个(或更多)函数定义为:
val functionM: String => Option[Int] = s => Some(s.length)
val functionM2: Int => Option[String] = i => Some(i.toString)
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我也有一些数据定义为:
val data: List[Option[String]] = List(Option("abc"))
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我的问题是如何组合(以一种很好的方式)函数来获得如下结果:
data.map(_.flatMap(functionM).flatMap(functionM2))
res0: List[Option[String]] = List(Some(3))
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我不喜欢上面函数调用的语法.如果我有很多像这样的地方那么代码是非常难以理解的.
我尝试使用OptionT scalaz monad转换器,但它仍然具有嵌套映射,并且还生成嵌套的选项,如:
OptionT(data).map(a => functionM(a).map(functionM2)).run
res2: List[Option[Option[Option[String]]]] = List(Some(Some(Some(3))))
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我想要达到的目标或多或少是这样的:
Something(data).map(functionM).map(functionM2)
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甚至更好:
val functions = functionM andThenSomething functionM2
Something(data).map(functions)
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如果它可以与Try一起使用会很好.据我所知,scalaz没有TryT monad变换器,所以有没有办法很好地组合在Try上运行的函数?
functional-programming scala monad-transformers function-composition scalaz
我们有一个 Rancher Kubernetes 集群,terminating当我们尝试删除相应的部署时,有时 pod 会卡在状态,如下所示。
$ kubectl get deployments
NAME DESIRED CURRENT UP-TO-DATE AVAILABLE AGE
...
storage-manager-deployment 1 0 0 0 1d
...
$ kubectl delete deployments storage-manager-deployment
kubectl delete deployments storage-manager-deployment
deployment.extensions "storage-manager-deployment" deleted
C-c C-c^C
$ kubectl get po
NAME READY STATUS RESTARTS AGE
...
storage-manager-deployment-6d56967cdd-7bgv5 0/1 Terminating 0 23h
...
$ kubectl delete pods storage-manager-deployment-6d56967cdd-7bgv5 --grace-period=0 --force
warning: Immediate deletion does not wait for confirmation that the running resource has been terminated. The resource …