從C＃調用F＃代碼

Question

我正在玩F＃和C＃，並希望從C＃調用F＃代碼。

我設法讓它在Visual Studio中以相反的方式工作，方法是在同一個解決方案中有兩個項目，並在F＃項目中添加C＃代碼的引用。 這樣做之后，我可以調用C＃代碼，甚至在調試時逐步執行它。

我想要做的是F＃代碼來自C＃而不是來自F＃的C＃代碼。 我在C＃項目中添加了對F＃項目的引用，但它的工作方式與以前不同。 我想知道如果不手動完成這是否可行。

Answer 1

下面是從C＃調用F＃的工作示例。

正如您所遇到的那樣，我無法通過從“添加引用...項目”選項卡中進行選擇來添加引用。 相反，我必須通過在“添加引用...瀏覽”選項卡中瀏覽到F＃程序集來手動完成。

------ F＃MODULE -----

// 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測試模塊-----

// 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);
        }

    }
}

Answer 2

它應該“正常工作”，盡管你可能必須在C＃的項目到項目引用工作之前構建F＃項目（我忘了）。

常見問題的根源是命名空間/模塊。 如果你的F＃代碼沒有以名稱空間聲明開頭，那么它會被放入一個與文件名同名的模塊中，這樣例如來自C＃你的類型可能會顯示為“Program.Foo”而不僅僅是“Foo”（如果是Foo）是Program.fs中定義的F＃類型。

Answer 3

從這個鏈接他們似乎有許多可能的解決方案，但似乎最簡單的解決方案是：

F＃代碼：

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＃代碼：

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

Answer 4

// Test.fs：

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：

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);