python - Is there anything similar to Python function decorators in F# programming language?

Question

I am learning F# and have some experience with Python. I really like Python function decorators; I was just wondering if we have anything similar to it in F#?

Answer 1

F# 中的函数装饰器没有语法糖。

对于类型，您可以使用StructuredFormatDisplay属性来自定义 printf 内容。下面是F# 3.0 Sample Pack中的一个示例：

[<StructuredFormatDisplayAttribute("MyType is {Contents}")>]
type C(elems: int list) =
   member x.Contents = elems

let printfnSample() = 
    printfn "%A" (C [1..4])

// MyType is [1; 2; 3; 4]

对于函数，您可以使用函数组合轻松表达Python 的装饰器。例如，这个 Python 示例

def makebold(fn):
    def wrapped():
        return "<b>" + fn() + "</b>"
    return wrapped

def makeitalic(fn):
    def wrapped():
        return "<i>" + fn() + "</i>"
    return wrapped

@makebold
@makeitalic
def hello():
    return "hello world"

可以翻译成F#如下

let makebold fn = 
    fun () -> "<b>" + fn() + "</b>"

let makeitalic fn =
    fun () -> "<i>" + fn() + "</i>"

let hello =
    let hello = fun () -> "hello world"
    (makebold << makeitalic) hello