README.md

This is a minimal complete example of Haskell being called from Visual C++

(or atleast its intended to be)

Motivation:

Needed to learn how to do this. Hopefully this will help someone out there trying to get Haskell from C++ running in visual studio.

Prerequists:

• Haskell Plaform Installed
• Visual Studio 2013
• Windows
• Patience

Usage:

Simply run packageHS.bat to get the what we need as .h and .lib files.

ghc -c Foozle.hs
ghc -c HsStartEnd.c
ghc -shared -o Foozle.dll Foozle.o HsStartEnd.o
lib /DEF:Foozle.def /OUT:Foozle.lib /MACHINE:x64

1. Compile Foozle.hs into Foozle.o and Foozle_stub.h
2. Compile HsStartEnd.c into HsStartEnd.o and HsStartEnd.h this is necissary because the commands to start and stop the STG (Spineless Tagless Graph Machine, (The thing that executes Haskell code)) cannot be called directly from C++, but they can be called form C.
3. Compile it all together into Foozle.dll
4. Generate Foozle.lib and Foozle.exp based on Foozle.def which can finally be called from C++

int main()
{
	HsStart(); // Start the STG
	std::cout << "Hello World!" << foo(3) << std::endl; // call foo from foozle.hs
	HsEnd(); // End the STG
	return 0; // Set a breakpoint here or something so you can see the result
}

You will also need to ensure that your VC++ Directories contains Haskell Platform, and that Your Linker > General > Input has Foozle.lib.