[英]Create local functions in F#
For example, I have 2 additive functions: 例如,我有2个附加功能:
module Add
let add2 a =
let innerFn a = a + 2
innerFn a
let add2' a =
let innerFn' () = a + 2
innerFn' ()
let res1 = add2 0
let res2 = add2' 1
From what I known, both innerFn
s will be compiled to FSharpFunc<int,int>
and FSharpFunc<unit,int>
respectively, and will be initialized everytime the add2
or add2'
is called. 根据我所知,两个
innerFn
将分别编译为FSharpFunc<int,int>
和FSharpFunc<unit,int>
,并且每次调用add2
或add2'
都会初始化。
How can I rewrite the code to transform them to static local functions of the static class (thus no FSharpFunc initialization), like in C# 7? 如何重写代码以将它们转换为静态类的静态本地函数(因此没有FSharpFunc初始化),就像在C#7中一样?
You probably don't have to worry about this. 你可能不必担心这个。 In a Debug build, every local function becomes a delegate.
在Debug构建中,每个本地函数都成为委托。 In a Release build, the functions are either inlined or do become static methods in the static class.
在发布版本中,函数被内联还是成为静态类的静态方法。
By building and decompiling the question's code in a Debug build, you get : 通过在Debug构建中构建和反编译问题的代码,您将获得:
public static int add2(int a)
{
return 5 + (new Program.innerFn@5()).Invoke(a);
}
public static int add2'(int a)
{
return (new Program.innerFn'@8(a)).Invoke(null);
}
Which does show a delegate initialization each time. 每次都会显示委托初始化。
In Release though, this becomes : 在Release中,这变为:
public static int add2(int a)
{
return a + 2;
}
public static int add2'(int a)
{
return a + 2;
}
The functions were inlined and no delegate was generated. 这些函数是内联的,没有生成任何委托。
To avoid indlining, I made add2
a bit more complex : 为了避免陷入困境,我使
add2
更加复杂:
let add2 a =
let innerFn a = if a < 3 then a+1 else a + 2
5 + innerFn a
let add2' a =
let innerFn' () = a + 2
innerFn' ()
In this case, the Release build generated a static method in the class : 在这种情况下,Release构建在类中生成了一个静态方法:
public static int add2(int a)
{
return 5 + Program.innerFn@5(a);
}
public static int add2'(int a)
{
return a + 2;
}
internal static int innerFn@5(int a)
{
if (a < 3)
{
return a + 1;
}
return a + 2;
}
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