Hello.

I’m new to stack & FFI.

I created a dll file by http://www.mingw.org/wiki/sampleDLL

And I put all files into dll folder. (Those files are example_dll.cpp, example_dll.dll, example_dll.h, example_dll.o, example_exe.cpp, libexample_dll.a) I test example_exe.exe file, and confirmed that works.

(Windows7 Pro, stack 1.9.3)

<package.yaml>

executables:

  test2-exe:

    main:                Main.hs

    source-dirs:         app

    ghc-options:

    - -threaded

    - -rtsopts

    - -with-rtsopts=-N

    dependencies:

    - test2

    extra-libraries:

    - example_dll.a

    extra-lib-dirs:

    - dll

<stack.yaml>

# Extra directories used by stack for building

extra-include-dirs:

  - dll

extra-lib-dirs:

  - dll

<Main.hs>

{-# LANGUAGE ForeignFunctionInterface #-}

 

module Main where

 

-- import Lib

import Foreign

 

foreign import ccall "example_dll.h hello"

    c_hello :: IO()

 

main :: IO ()

main = c_hello

<example_dll.cpp>

#include <stdio.h>

#include "example_dll.h"

 

__stdcall void hello(const char *s)

{

        printf("Hello %s\n", s);

}

int Double(int x)

{

        return 2 * x;

}

void CppFunc(void)

{

        puts("CppFunc");

}

void MyClass::func(void)

{

        puts("MyClass.func()");

}

 

When I try to stack build, I get error messages.

 

C:\Users\shaegis\Documents\Haskell\test2\dll>stack build

Building all executables for `test2' once. After a successful build of all of them, only specified executables will be rebuilt.

test2-0.1.0.0: configure (lib + exe)

Configuring test2-0.1.0.0...

Cabal-simple_Z6RU0evB_2.4.0.1_ghc-8.6.3.exe: Missing dependency on a foreign

library:

* Missing (or bad) C library: example_dll.a

This problem can usually be solved by installing the system package that

provides this library (you may need the "-dev" version). If the library is

already installed but in a non-standard location then you can use the flags

--extra-include-dirs= and --extra-lib-dirs= to specify where it is.If the

library file does exist, it may contain errors that are caught by the C

compiler at the preprocessing stage. In this case you can re-run configure

with the verbosity flag -v3 to see the error messages.

 

--  While building package test2-0.1.0.0 using:

      C:\sr\setup-exe-cache\x86_64-windows\Cabal-simple_Z6RU0evB_2.4.0.1_ghc-8.6.3.exe --builddir=.stack-work\dist\e626a42b configure --with-ghc=C:\Users\shaegis\AppData\Local\Programs\stack\x86_64-windows\ghc-8.6.3\bin\ghc.EXE --with-ghc-pkg=C:\Users\shaegis\AppData\Local\Programs\stack\x86_64-windows\ghc-8.6.3\bin\ghc-pkg.EXE --user --package-db=clear --package-db=global --package-db=C:\sr\snapshots\3233b5e2\pkgdb --package-db=C:\Users\shaegis\Documents\Haskell\test2\.stack-work\install\784ab3f0\pkgdb --libdir=C:\Users\shaegis\Documents\Haskell\test2\.stack-work\install\784ab3f0\lib --bindir=C:\Users\shaegis\Documents\Haskell\test2\.stack-work\install\784ab3f0\bin --datadir=C:\Users\shaegis\Documents\Haskell\test2\.stack-work\install\784ab3f0\share --libexecdir=C:\Users\shaegis\Documents\Haskell\test2\.stack-work\install\784ab3f0\libexec --sysconfdir=C:\Users\shaegis\Documents\Haskell\test2\.stack-work\install\784ab3f0\etc --docdir=C:\Users\shaegis\Documents\Haskell\test2\.stack-work\install\784ab3f0\doc\test2-0.1.0.0 --htmldir=C:\Users\shaegis\Documents\Haskell\test2\.stack-work\install\784ab3f0\doc\test2-0.1.0.0 --haddockdir=C:\Users\shaegis\Documents\Haskell\test2\.stack-work\install\784ab3f0\doc\test2-0.1.0.0 --dependency=base=base-4.12.0.0 --extra-include-dirs=C:\Users\shaegis\AppData\Local\Programs\stack\x86_64-windows\msys2-20180531\mingw64\include --extra-include-dirs=C:\Users\shaegis\Documents\Haskell\test2\dll --extra-lib-dirs=C:\Users\shaegis\AppData\Local\Programs\stack\x86_64-windows\msys2-20180531\mingw64\bin --extra-lib-dirs=C:\Users\shaegis\AppData\Local\Programs\stack\x86_64-windows\msys2-20180531\mingw64\lib --extra-lib-dirs=C:\Users\shaegis\Documents\Haskell\test2\dll --enable-tests --enable-benchmarks

Process exited with code: ExitFailure 1

 

How can I fix this? I did a lot of things on the webpages, but I could not.

Please, help me.

 

Sincerely, S. Chang.