F#中的底部/未定义值? [英] Bottom/undefined value in F#?

问题描述

Haskell中有一个方便的 undefined 值，可用作尚未定义的函数/路径的存根.在代码中. F#中有类似的东西吗?

There is a convenient undefined value in Haskell that can be used as a stub for yet to be defined functions/paths in code. Is there anything like it in F#?

推荐答案

具体来说，您可以定义这样的值:

To be concrete, you can define such a value like this:

let undefined<'T> : 'T = failwith "Not implemented yet"

let stub1 (x : int) : float = undefined
let stub2 (x : 'T) : 'T = undefined

请注意，F#评估是严格的.如果将undefined绑定到顶级值，它将在评估期间引发异常.

Beware that F# evaluation is strict. If you bind undefined to a top-level value, it will throw an exception during evaluation.

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