从 C# 调用 F# 代码

Call F# code from C#

提问by ZeroKelvin

I am playing around with F# and C#, and would like to call F# code from C#.

我正在玩 F# 和 C#，并想从 C# 调用 F# 代码。

I managed to get it to work the other way around in Visual Studio by having two projects in the same solution, and adding a reference of the C# code to the F# project. After doing this, I could call C# code and even step through it while debugging.

通过在同一个解决方案中有两个项目，并将 C# 代码的引用添加到 F# 项目，我设法让它在 Visual Studio 中以相反的方式工作。执行此操作后，我可以调用 C# 代码，甚至可以在调试时单步执行。

What I am trying to do is F# code FROM C# instead of C# code from F#. I added a reference to the F# project to the C# project, but it isn't working the way it did before. I would like to know if this is possible without doing it manually.

我想要做的是来自 C# 的 F# 代码，而不是来自 F# 的 C# 代码。我向 C# 项目添加了对 F# 项目的引用，但它无法像以前那样工作。我想知道这是否可以不手动进行。

采纳答案by Eric

Below is a working example of calling F# from C#.

下面是一个从 C# 调用 F# 的工作示例。

As you encountered, I was not able to add a reference by selecting from the "Add Reference ... Projects" tab. Instead I did have to do it manually, by browsing to the F# assembly in the "Add Reference ... Browse" tab.

正如您所遇到的，我无法通过从“添加引用...项目”选项卡中进行选择来添加引用。相反，我确实必须手动完成，方法是在“添加引用...浏览”选项卡中浏览到 F# 程序集。

------ F# MODULE -----

------ F# 模块 -----

// First implement a foldl function, with the signature (a->b->a) -> a -> [b] -> a
// Now use your foldl function to implement a map function, with the signature (a->b) -> [a] -> [b]
// Finally use your map function to convert an array of strings to upper case
//
// Test cases are in TestFoldMapUCase.cs
//
// Note: F# provides standard implementations of the fold and map operations, but the 
// exercise here is to build them up from primitive elements...

module FoldMapUCase.Zumbro
#light


let AlwaysTwo =
   2

let rec foldl fn seed vals = 
   match vals with
   | head :: tail -> foldl fn (fn seed head) tail
   | _ -> seed


let map fn vals =
   let gn lst x =
      fn( x ) :: lst
   List.rev (foldl gn [] vals)


let ucase vals =
   map String.uppercase vals

----- C# UNIT TESTS FOR THE MODULE -----

----- 模块的 C# 单元测试 -----

// Test cases for FoldMapUCase.fs
//
// For this example, I have written my NUnit test cases in C#.  This requires constructing some F#
// types in order to invoke the F# functions under test.


using System;
using Microsoft.FSharp.Core;
using Microsoft.FSharp.Collections;
using NUnit.Framework;

namespace FoldMapUCase
{
    [TestFixture]
    public class TestFoldMapUCase
    {
        public TestFoldMapUCase()
        {            
        }

        [Test]
        public void CheckAlwaysTwo()
        {
            // simple example to show how to access F# function from C#
            int n = Zumbro.AlwaysTwo;
            Assert.AreEqual(2, n);
        }

        class Helper<T>
        {
            public static List<T> mkList(params T[] ar)
            {
                List<T> foo = List<T>.Nil;
                for (int n = ar.Length - 1; n >= 0; n--)
                    foo = List<T>.Cons(ar[n], foo);
                return foo;
            }
        }


        [Test]
        public void foldl1()
        {
            int seed = 64;
            List<int> values = Helper<int>.mkList( 4, 2, 4 );
            FastFunc<int, FastFunc<int,int>> fn =
                FuncConvert.ToFastFunc( (Converter<int,int,int>) delegate( int a, int b ) { return a/b; } );

            int result = Zumbro.foldl<int, int>( fn, seed, values);
            Assert.AreEqual(2, result);
        }

        [Test]
        public void foldl0()
        {
            string seed = "hi mom";
            List<string> values = Helper<string>.mkList();
            FastFunc<string, FastFunc<string, string>> fn =
                FuncConvert.ToFastFunc((Converter<string, string, string>)delegate(string a, string b) { throw new Exception("should never be invoked"); });

            string result = Zumbro.foldl<string, string>(fn, seed, values);
            Assert.AreEqual(seed, result);
        }

        [Test]
        public void map()
        {
            FastFunc<int, int> fn =
                FuncConvert.ToFastFunc((Converter<int, int>)delegate(int a) { return a*a; });

            List<int> vals = Helper<int>.mkList(1, 2, 3);
            List<int> res = Zumbro.map<int, int>(fn, vals);

            Assert.AreEqual(res.Length, 3);
            Assert.AreEqual(1, res.Head);
            Assert.AreEqual(4, res.Tail.Head);
            Assert.AreEqual(9, res.Tail.Tail.Head);
        }

        [Test]
        public void ucase()
        {
            List<string> vals = Helper<string>.mkList("arnold", "BOB", "crAIg");
            List<string> exp = Helper<string>.mkList( "ARNOLD", "BOB", "CRAIG" );
            List<string> res = Zumbro.ucase(vals);
            Assert.AreEqual(exp.Length, res.Length);
            Assert.AreEqual(exp.Head, res.Head);
            Assert.AreEqual(exp.Tail.Head, res.Tail.Head);
            Assert.AreEqual(exp.Tail.Tail.Head, res.Tail.Tail.Head);
        }

    }
}

回答by Chris Bunch

From this linkthey seem to have a number of possible solutions, but the one that seemed the simplest was a comment:

从这个链接他们似乎有许多可能的解决方案，但似乎最简单的一个是评论：

F# Code:

F# 代码：

type FCallback = delegate of int*int -> int;;
type FCallback =
  delegate of int * int -> int

let f3 (f:FCallback) a b = f.Invoke(a,b);;
val f3 : FCallback -> int -> int -> int

C# Code:

C# 代码：

int a = Module1.f3(Module1.f2, 10, 20); // method gets converted to the delegate automatically in C#

回答by Brian

It should 'just work', though you might have to build the F# project before a project-to-project reference from C# works (I forget).

它应该“正常工作”，尽管您可能必须在 C# 的项目到项目引用工作之前构建 F# 项目（我忘记了）。

A common source of issues is namespaces/modules. If your F# code does not start with a namespace declaration, it gets put in a module with the same name as the filename, so that e.g. from C# your type might appear as "Program.Foo" rather than just "Foo" (if Foo is an F# type defined in Program.fs).

一个常见的问题来源是命名空间/模块。如果您的 F# 代码没有以命名空间声明开头，则会将其放入与文件名同名的模块中，因此例如从 C# 中，您的类型可能显示为“Program.Foo”而不仅仅是“Foo”（如果 Foo是在 Program.fs 中定义的 F# 类型）。

回答by merrais

// Test.fs :

// 测试文件：

module meGlobal

type meList() = 
    member this.quicksort = function
        | [] -> []  //  if list is empty return list
        | first::rest -> 
            let smaller,larger = List.partition((>=) first) rest
        List.concat[this.quicksort smaller; [first]; this.quicksort larger]

// Test.cs :

// 测试.cs :

List<int> A = new List<int> { 13, 23, 7, 2 };
meGlobal.meList S = new meGlobal.meList();

var cquicksort = Microsoft.FSharp.Core.FSharpFunc<FSharpList<IComparable>,     FSharpList<IComparable>>.ToConverter(S.quicksort);

FSharpList<IComparable> FI = ListModule.OfSeq(A.Cast<IComparable>());
var R = cquicksort(FI);