有没有办法在纯函数中放置一些不纯的代码? [英] Is there a way to place some impure code inside pure functions?

问题描述

IO，就像Maybe一样，只是Monad的一个实例.另一方面，我们有 Maybe(Just 和 Nothing)的所有数据构造函数，但没有 IO 的构造函数.Reader 和 Writer 也不导出构造函数，它们有函数，返回该类型的实例(reader 和 writer>) 以及更重要的 runReader 和 runWriter，它们解开 Monad 的计算结果.

IO, just like Maybe, is just an instance of Monad. On the other hand we have all data constructors for Maybe (Just and Nothing), but no constructors for IO. Reader and Writer do not export constructors too, they have functions, which return instance of this type (reader and writer) and more importantly runReader and runWriter, which unwrap computation result from Monad.

有没有办法解开 IO Monad?我想要纯函数，它在幕后做一些不纯的 IO 计算.目前我可以用大多数 Monads 做到这一点

Is there a way to unwrap IO Monad? I would like to have pure function which do some impure IO computations under the hood. Currently I am able to do this with most of the Monads

我知道一个这样棘手的函数的例子:Debug.Trace.trace

I know one example of such tricky function: Debug.Trace.trace

推荐答案

unsafePerformIO :: IO a ->System.IO.Unsafe(基础)中的一个.

unsafePerformIO :: IO a -> a in System.IO.Unsafe (base).

谨慎使用并阅读文档 仔细.

Use it with caution and read the description in the documentation carefully.

这篇关于有没有办法在纯函数中放置一些不纯的代码?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！