[Haskell-beginners] Same code, system, but different arch using Win32 for reading registry.

[Akos Marton]

Dear Haskellers,

The setup:
Having a binary compiled on either x86 or x64 system (same installation, 
utilizing stack) in order to preserve compatibility against x64 systems. 
Actually, not to have 2 separate executable for each, that would be the 
overall goal. However it surprises me when running the x86 .exe 
utilizing Win32-2.5.4.1 package with ghc-8.0.2, reading out a registry 
key fails on x64 system with the following:/
/

/me.exe: RegOpenKey: invalid argument (The system cannot find the file 
specified.)/

That would be fine, however the key does exists. When same code, same 
system, but the .exe built to be x64 it runs like a charm.

A couple of question, which some of them eventually will not make sense, 
but still:
- Can it be ghc code optimization issue?
- but this is a runtime check in IO, if so, how?
- Yes, I could use a built-in windows system command and parse the input 
of that; unless absolutely necessary I would not introduce another 
dependency (system package). Would love to solve it with the currently 
utilized weapons.
- the issue just puzzles me... I would know the answer if possible.
- Is it more library (Win32), ghc, binary I generate, issue?

What library can I use to detect a system's architecture which works in 
this scenario?

Another thing which convoluted in the issue...
The function, /getSystemInfo :: IO SYSTEM_INFO, /can read out the 
underlying architecture. When compiled on x86 and run on x64 it would 
tell me: "I am running on x86". That's failure.

Most importantly: what is the obvious I am missing?

Thank you for your insights!
Best, Akos



Ps.: Would you/we need sample code to puzzle about I can quickly weld 
one. - not sure if necessary.
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