使Test.QuickCheck.Batch使用默认类型来测试列表函数

I am testing a function called extractions that operates over any list.

我正在测试一个名为提取的函数,它可以在任何列表上运行。

extractions :: [a] -> [(a,[a])]
extractions [] = []
extractions l = extract l []
    where extract [] _ = []
          extract (x:xs) prev = (x, prev++xs) : extract xs (x : prev)

I want to test it, for example, with

我想测试它,例如,用

import Test.QuickCheck.Batch    
prop_len l = length l == length (extractions l)
main = runTests "extractions" defOpt [run prop_len]

But this won't compile; I have to supply a type either for run or prop_len, because QuickCheck can't generate [a], it has to generate something concrete. So I chose Int:

但这不会编译;我必须为run或prop_len提供一个类型,因为QuickCheck不能生成[a],它必须生成具体的东西。所以我选择了Int:

main = runTests "extractions" defOpt [r prop_len]
    where r = run :: ([Int] -> Bool) -> TestOptions -> IO TestResult

Is there any way to get QuickCheck to choose a for me instead of having it specified in the type of run?

有没有办法让QuickCheck为我选择一个而不是在运行类型中指定它?

1 个解决方案

#1

The quickcheck manual says "no":

quickcheck手册说“不”:

Properties must have monomorphic types. `Polymorphic' properties, such as the one above, must be restricted to a particular type to be used for testing. It is convenient to do so by stating the types of one or more arguments in a

属性必须具有单形类型。 “多态”属性(例如上面的属性)必须限制为用于测试的特定类型。通过在a中声明一个或多个参数的类型来方便

where types = (x1 :: t1, x2 :: t2, ...)

其中types =(x1 :: t1,x2 :: t2,...)

clause...