[Haskell-cafe] Windows: how to perform cleanup actions when the console window closes

[Joachim Durchholz]

Am 06.04.2018 um 10:09 schrieb Peter Dedecker:
> Summary question and TLDR: how do I reliably perform cleanup actions in 
> a Windows console program that is closed by the user by clicking the 'X' 
> symbol in the window title bar?

You need to intercept the various events that may cause a console 
windows to be closed; this is done via the Windows API call 
SetConsoleCtrlHandler .
https://stackoverflow.com/a/30843219/6944068 gives an overview, API doc 
is at 
https://docs.microsoft.com/en-us/windows/console/setconsolectrlhandler 
(you want to register a HandlerRoutine).

The default handler simply calls ExitProcess, bypassing all shutdown 
activity of the runtime. That's why C++ guys complain that destructors 
are not called.

I don't know how to register a Haskell function as a Windows callback, 
that will have to be answered by somebody else.

HTH
Jo