如何从FsCheck.Gen.choose中提取int [英] How extract the int from a FsCheck.Gen.choose

问题描述

我是F#的新手，看不到如何从以下方法提取int值:

I'm new on F#, and can't see how extract the int value from:

let autoInc = FsCheck.Gen.choose(1,999)

编译器说类型是Gen<int>，但是无法从中获取int!.我需要将其转换为十进制，并且两种类型都不兼容.

The compiler say the type is Gen<int>, but can't get the int from it!. I need to convert it to decimal, and both types are not compatible.

推荐答案

从消费者的角度来看，您可以使用Gen.sample组合器，该组合器在给定生成器(例如Gen.choose)的情况下，为您提供了一些示例值

From a consumer's point of view, you can use the Gen.sample combinator which, given a generator (e.g. Gen.choose), gives you back some example values.

Gen.sample的签名是:

val sample : size:int -> n:int -> gn:Gen<'a> -> 'a list

(* `size` is the size of generated test data
   `n`    is the number of samples to be returned
   `gn`   is the generator (e.g. `Gen.choose` in this case) *)

您可以忽略size，因为Gen.choose会忽略它，因为它的分布是均匀的，并且可以执行以下操作:

You can ignore size because Gen.choose ignores it, as its distribution is uniform, and do something like:

let result = Gen.choose(1,999) |> Gen.sample 0 1 |> Seq.exactlyOne |> decimal

(* 0 is the `size` (gets ignored by Gen.choose)
   1 is the number of samples to be returned *)

result应该是封闭时间间隔 [1，999] 中的一个值，例如 897 .

The result should be a value in the closed interval [1, 999], e.g. 897.

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