Simulating keystrokes with Haskell on Windows - winapi

Question

I am trying to write a Haskell program that simulates keystrokes on Windows. I tried to call keybd_event and SendInput, but neither one compiled. I can run the program with the interpreter, though. When I try to build the program when it contains a binding to SendInput in winable.h, I get the error:
cabal install
...
[1 of 2] Compiling WindowsKeys ( dist\build\WindowsKeys\WindowsKeys-tmp\WindowsKeys.hs, dist\build\WindowsKeys\WindowsKeys-tmp\WindowsKeys.o )
[2 of 2] Compiling Main ( src\Main.hs, dist\build\WindowsKeys\WindowsKeys-tmp\Main.o )
Linking dist\build\WindowsKeys\WindowsKeys.exe ...
dist\build\WindowsKeys\WindowsKeys-tmp\WindowsKeys.o:fake:(.text+0x35d): undefined reference to `SendInput'
collect2: ld returned 1 exit status
cabal: Error: some packages failed to install:
WindowsKeys-0.1.0.0 failed during the building phase. The exception was:
ExitFailure 1
The verbose error is at http://pastebin.com/trg21N0x , but it doesn't seem to contain any more clues. I get a similar error when I try to use keybd_event.
The hsc file I wrote includes these headers:
#include "windows.h"
#include "winuser.h"
#include "winable.h"
Here is the C binding:
foreign import ccall unsafe "winable.h SendInput"
c_SendInput :: UINT
-> Ptr Input
-> CInt
-> IO UINT
I assumed that I could not call SendInput on winuser.h because of the #if :
#if (_WIN32_WINNT >= 0x0403)
WINUSERAPI UINT WINAPI SendInput(UINT,LPINPUT,int);
When I add a binding for _WIN32_WINNT , the value is 0x400.
I have version 2012.4.0.0 of the Haskell Platform. It came with a folder of headers containing the ones that I included. I could not find any other headers with the same names on my computer. I am using Windows 7 Professional, version 6.1 .
Thank you!
Here is WindowsKeys.cabal :
-- Initial WindowsKeys.cabal generated by cabal init. For further
-- documentation, see http://haskell.org/cabal/users-guide/
name: WindowsKeys
version: 0.1.0.0
build-type: Simple
cabal-version: >=1.8
extra-source-files: windows.h, winuser.h, winable.h
executable WindowsKeys
main-is: Main.hs
other-modules: WindowsKeys
build-depends: base ==4.5.*, Win32 ==2.2.*
hs-source-dirs: src
build-tools: hsc2hs
extra-libraries: user32
include-dirs: src
The build succeeds when I comment out the bindings to the keyboard functions.

Answer 1

I finally found that I had used the wrong calling convention. keybd_event and SendInput both need to be called with stdcall instead of ccall.