Question

我想撰写一些返回Scalaz 7 Validation的检查。我做了一个简单的例子，解析一系列单词并从中构造一个Person对象。解析可能会在很多步骤中失败，在这种情况下我们会快速失败，并显示失败的错误消息。下面的例子是完全弥补和愚蠢的，但是尽可能接近我想要达到的目标。

看看下面的理解，似乎必须有更好的方法来构建验证。

初始序列更改了几次，从seq更改为seq2到seq3。在调用示例lastNameValidation时，需要使用seq2显式调用它，即使它在seq2 = onlyShort(seq)之后立即调用。
我读到有关Kleisli箭头构图的内容，当人们可以撰写A => M[B]和B => M[C]来获得箭头A => M[C]（其中M是monad）。但是，我并不总是以这样的方式组合事物，即下一步将重复使用前一步的计算。那，并且我无法使用Scalaz 7获得Kleisli箭头组合。

代码：

import scalaz._, Scalaz._

case class Address(streetName: String, streetNumber: Int)
case class Person(name: String, lastName: String, age: Int, address: Address)

def nameValidation(seq: List[String]) = seq.find(Set("John", "Carol", "Susan").contains(_)).toSuccess("Name not found")
def lastNameValidation(seq: List[String]) = seq.find(Set("Kennedy", "Hardy", "Taplin").contains(_)).toSuccess("Last name not found")
def lengthValidation(lastName: String) = lastName.size.success[String]
def dyValidation(lastName: String) = if (!lastName.contains("dy")) Failure("Not the person") else Success(123)
def streetNumberValidation(seq: List[String]) = seq.find(_.forall(_.isDigit)).map(_.toInt).toSuccess("Could not extract street number")
def streetValidation(seq: List[String]) = seq.find(Set("Bush Street", "Pine Street", "Market Street").contains(_)).toSuccess("Street not found")

def onlyShort(seq: List[String]) = seq.filter(_.size < 15)
def omitGarbage(seq: List[String]) = seq.filter(_ != "garbage")

def createPerson(seq: List[String]) = for {
  name <- nameValidation(seq)
  seq2 = onlyShort(seq)
  lastName <- lastNameValidation(seq2)
  length <- lengthValidation(lastName)
  dy <- dyValidation(lastName)
  seq3 = omitGarbage(seq2)
  streetNumber <- streetNumberValidation(seq3)
  street <- streetValidation(seq3)
} yield Person(name, lastName, 80, Address(street, streetNumber))

createPerson(List("255", "a very long string", "Bush Street", "Hardy", "San Francisco", "John", "garbage"))

createPerson(List("a very long string", "Bush Street", "Hardy", "San Francisco", "John", "garbage"))

非常欢迎任何scalaz / functional guru的建议！

REPL：

scala> import scalaz._, Scalaz._
import scalaz._
import Scalaz._

scala> case class Address(streetName: String, streetNumber: Int)
defined class Address

scala> case class Person(name: String, lastName: String, age: Int, address: Address)
defined class Person

scala> def nameValidation(seq: List[String]) = seq.find(Set("John", "Carol", "Susan").contains(_)).toSuccess("Name not found")
nameValidation: (seq: List[String])scalaz.Validation[java.lang.String,String]

scala> def lastNameValidation(seq: List[String]) = seq.find(Set("Kennedy", "Hardy", "Taplin").contains(_)).toSuccess("Last name not found")
lastNameValidation: (seq: List[String])scalaz.Validation[java.lang.String,String]

scala> def lengthValidation(lastName: String) = lastName.size.success[String]
lengthValidation: (lastName: String)scalaz.Validation[String,Int]

scala> def dyValidation(lastName: String) = if (!lastName.contains("dy")) Failure("Not the person") else Success(123)
dyValidation: (lastName: String)Product with Serializable with scalaz.Validation[java.lang.String,Int]

scala> def streetNumberValidation(seq: List[String]) = seq.find(_.forall(_.isDigit)).map(_.toInt).toSuccess("Could not extract street number")
streetNumberValidation: (seq: List[String])scalaz.Validation[java.lang.String,Int]

scala> def streetValidation(seq: List[String]) = seq.find(Set("Bush Street", "Pine Street", "Market Street").contains(_)).toSuccess("Street not found")
streetValidation: (seq: List[String])scalaz.Validation[java.lang.String,String]

scala> def onlyShort(seq: List[String]) = seq.filter(_.size < 15)
onlyShort: (seq: List[String])List[String]

scala> def omitGarbage(seq: List[String]) = seq.filter(_ != "garbage")
omitGarbage: (seq: List[String])List[String]

scala> def createPerson(seq: List[String]) = for {
     |   name <- nameValidation(seq)
     |   seq2 = onlyShort(seq)
     |   lastName <- lastNameValidation(seq2)
     |   length <- lengthValidation(lastName)
     |   dy <- dyValidation(lastName)
     |   seq3 = omitGarbage(seq2)
     |   streetNumber <- streetNumberValidation(seq3)
     |   street <- streetValidation(seq3)
     | } yield Person(name, lastName, 80, Address(street, streetNumber))
createPerson: (seq: List[String])scalaz.Validation[java.lang.String,Person]

scala> createPerson(List("255", "a very long string", "Bush Street", "Hardy", "San Francisco", "John", "garbage"))
res19: scalaz.Validation[java.lang.String,Person] = Success(Person(John,Hardy,80,Address(Bush Street,255)))

scala> createPerson(List("a very long string", "Bush Street", "Hardy", "San Francisco", "John", "garbage"))
res20: scalaz.Validation[java.lang.String,Person] = Failure(Could not extract street number)

编写Scalaz 7验证

0 个答案: