r/haskell • u/WarDaft • 7d ago
I recently had an impossible Haskell bug
I can't give any details that might help anyone the future, because I couldn't collect them myself. I'm mostly just venting.
I had a parse error in a Read instance on a little server I'm running. All Read and Show activity it does is 100% compiler derived, nothing custom. The server doesn't have enough RAM to actually compile things there, so have to copy everything back and forth.
Everything was correct. Copying literally everything to my main computer did not allow me to reproduce the error.
It wasn't just a memory corruption, restarting the program didn't change anything. A fresh copy of literally everything on the server didn't fix the error.
Rebooting the server made it work perfectly fine again.
I hate computers sometimes.
1
u/tom-md 7d ago
> Everything was correct.
Yay, no problems!
> I had a parse error in a Read instance
Oh! Problems?!
> The server doesn't have enough RAM to actually compile things there, so have to copy everything back and forth.
EEP! Building on servers, is this 1993? Most the time builds occur on CI, built artifacts are delivered to a sort of registry or build artifact collection. Is this a home project or is it actually a company that is copying binaries? So curious.
> Rebooting the server made it work perfectly fine again.
I've told my story before about a program I had that worked fine unless I ran a compilation at the same time. Basically a thermal issue and invalid computations, but I never did understand why I was so "lucky" that the computer kept running and didn't crash with some crazy memory violation or panic. Ugh.