Haskell评估期限 [英] Haskell Time Limit on Evaluation

问题描述

没有人知道一个仅允许一定时间执行功能的功能.具有这种类型签名的东西.

Does anyone know of a function that will allow only a certain amount of time to execute a function. Something with a type signature like this.

limited::Int->(a->b)->a->IO (Maybe b)

我想不出如何实现，也找不到.我问的原因是，我将列出所有可能的 Brainfuck 程序的列表，以及我想过滤掉花费太长时间的内容.

I can't think of how to implement, and I couldn't find it. The reason why I ask is I am going to make a list of all possible Brainfuck programs, and I want to filter out the ones that take too long.

推荐答案

System中有专用功能超时:

There's a dedicated function from System.Timeout:

timeout :: Int -> IO a -> IO (Maybe a)

使用您的书写方式，只需使用

To have it the way you wrote, just use

limited t f x = timeout t $ do
     let y = f x
     y `seq` return y

请记住，Haskell的懒惰意味着任何值都被其他语言称为零参数的记忆函数"，因此您实际上并不需要(a->b) -> a ->.

Remember that Haskell's laziness means any value is what other languages might call "memoised function of zero arguments", so you don't really need the (a->b) -> a ->.

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