问题描述
我有一个F#功能,我想尝试改变一些参数并测试所有这些组合。这是正确的方法吗? (括号变得有点密集......):
I have an F# function and I want to try varying some of the parameters and testing all such combinations. Is this the right approach? (The parentheses get a bit dense...):
let MyFunc a b c x y z =
...
q
let UploadResult a b c x y z q =
...
()
let a = 5.0
let b = 0
let c = System.DateTime.Today
let xList = [-1.0; 0.0; 1.0]
let yList = [2; 4; 6; 8; 10]
let zList = [0.1; 0.001]
xList |> List.iter (fun x ->
(yList |> List.iter (fun y ->
(zList |> List.iter (fun z ->
MyFunc a b c x y z
|> UploadResult a b c x y z ))) ))
|> ignore
所以我想上传3x5x2 = 30个结果,然后写得很好。谢谢你的建议。
So I want to upload 3x5x2=30 results, and write it nicely. Thanks for any advice.
推荐答案
实际上,您的主要目标是创建跨产品(或笛卡儿多个列表的产品),在F#开发人员中有几个选项被认为是良好实践:
In fact, your primary goal is creating a Cross-Product (or Cartesian Product) of several lists, and there are several options considered "good practice" among F# developers:
1。 (已删除
-comprehension,因为其他答案已经建议了这一点)
1. (removed for
-comprehension as other answer already suggested this)
2。使用计算表达式(在函数式编程世界的其余部分,通常称为 Monad ):
2. Use Computation Expressions (in the rest of Functional Programming world, it is often called Monad):
type Product () =
member this.Bind (l,f) = List.collect f l
member this.Return n = [n]
let ret02 = Product() {
let! x = xList
let! y = yList
let! z = zList
MyFunc a b c x y z
|> UploadResult a b c x y z
}
3。如果您只是担心括号,请使用高优先级,右关联反向管道,()
3. If you only worry about parentheses, use the high precedence, right associative backward pipe, (more info)
let inline (^<|) f a = f a
然后,您的代码需要进行最小的修改(尽管仍然不是很干净):
Then, your code would need a minimal modification (albeit still not very clean):
let ret03 =
xList |> List.iter ^<| fun x ->
yList |> List.iter ^<| fun y ->
zList |> List.iter ^<| fun z ->
MyFunc a b c x y z
|> UploadResult a b c x y z
|> ignore
这篇关于F#嵌套List.iter调用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!