从Haskell调用DLL [英] Call a DLL from Haskell

问题描述

我有一个名为 Foo.dll的Windows DLL / / code>。它导出（其他东西）以下内容：

I have a Windows DLL named Foo.dll. It exports (amoung other things) the following:

extern "C" __declspec(dllexport) unsigned int Version();

如何编写一个调用此函数并打印出答案的Haskell程序？

How do I write a Haskell program which calls this function and prints out the answer?

我设法弄清楚我可以写这个：

I managed to figure out that I can write this:

foreign import ccall "Version" cpp_Version :: CUInt

这个编译很好，但是完全无法链接。这并不奇怪在这一点上，GHC没有想到在哪里找到这个功能。但是我无法确定我需要推动什么魔术按钮来实现这一点。有没有人可以告诉我如何建立成功？

This compiles just fine, but utterly fails to link. This is not surprising; at this point GHC has no idea where the hell to look for this function. But I can't figure out what magic button I need to push to make this happen. Can anybody tell me how to get this to build sucessfully?

（我也不能100％确定调用约定应该是 ccall 或 stdcall ;有什么区别？）

(I'm also not 100% sure whether the calling convention should be ccall or stdcall; what's the difference?)

推荐答案

p>使用以下选项进行编译出现：

ghc -O2 -L. -lFoo --make Wrapper

似乎添加 -lFoo 告诉GHC寻找一个 Foo.dll 文件，并添加 -L。告诉它包含DLL搜索路径中的当前目录。

It appears that adding -lFoo tells GHC to look for a Foo.dll file, and adding -L. tells it to include the current directory in the DLL search path.

我不是100％确定这是否在运行时加载DLL，或者实际上将DLL的代码静态链接到二进制文件。 （!!）

I am not 100% sure whether this is loading the DLL at runtime, or actually statically linking the DLL's code into the binary somehow. (!!)

将 ccall 更改为 stdcall 一些警告将被发出（但编译代码仍然正常工作）。因此，它出现， ccall 是正确的。

Changing ccall to stdcall causes a bunch of warnings to be emitted (but the compiled code still works correctly). Thus, it appears that ccall is the correct thing.

我还是会赞赏如果有人可以仔细检查我写的是不是完整的废话...

I would still appreciate it if somebody could double-check that what I've written isn't complete nonsense...

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