这些模式对我来说看起来很详尽,"非详尽模式错误"？为什么？

Question

问题

在从Haskell书中记笔记时,这个代码示例应该返回:Left [NameEmpty, AgeTooLow],但它只返回第一个案例Left [NameEmpty].然后,当我传递mkPerson2它应该返回的函数结果时Right Person _ _,我得到了一个"非详尽模式``错误.我已经查看了这段代码很长一段时间了,但它对我来说是正确的.我在这里错过了什么？关于这个问题的任何解释都将非常感谢,谢谢!

我正在使用的书

码

module EqCaseGuard where

type Name = String
type Age  = Integer
type ValidatePerson a = Either [PersonInvalid] a

data Person = Person Name Age deriving Show

data PersonInvalid = NameEmpty
                   | AgeTooLow
                   deriving Eq

ageOkay :: Age -> Either [PersonInvalid] Age
ageOkay age = case age >= 0 of
True  -> Right age
False -> Left [AgeTooLow]

nameOkay :: Name -> Either [PersonInvalid] Name
nameOkay name = case name /= "" of
True  -> Right name
False -> Left [NameEmpty]

mkPerson2 :: Name -> Age -> ValidatePerson Person
mkPerson2 name age = mkPerson2' (nameOkay name) (ageOkay age)

mkPerson2' :: ValidatePerson Name -> ValidatePerson Age -> ValidatePerson Person
mKPerson2' (Right nameOk) (Right ageOk) = Right (Person nameOk ageOk)
mKPerson2' (Left badName) (Left badAge) = Left (badName ++ badAge)
mkPerson2' (Left badName)  _            = Left badName
mkPerson2' _              (Left badAge) = Left badAge

错误

*EqCaseGuard> mkPerson2 "jack" 22
*** Exception: eqCaseGuard.hs:(54,1)-(55,53): Non-exhaustive patterns in function mkPerson2'

*EqCaseGuard> mkPerson2 "" (-1)
Left [NameEmpty]
*EqCaseGuard> 

Answer 1

您在前两个定义中使用了大写字母K:

mKPerson2' (Right nameOk) (Right ageOk) = Right (Person nameOk ageOk)
 ^

mKPerson2' (Left badName) (Left badAge) = Left (badName ++ badAge)
 ^