Is this library safe?

[martyall]

I usually blindly trust anything with the name kmett attached, but I'm experiencing some behavior where distinct interned values come back with the same Id. I can verify that they belong to the same cache bucket (i.e. their modulus is the same wrt the cacheWidth) and that they have distinct hashes.

The setup for my work is open source but it's quite involved. I can share code if needed but looking for a high level answer first. I'm not an unsafePerformIO guru, but under what conditions is using intern safe? Are race conditions possible? Can compiler optimizations effect the outcome?

In fact, since this whole thing is predicated based on unique Int hashes, why have this Id be some formulaic incremented value instead of just using hash . describe ?

NOTE: When I stop using the formula based on current cache state for the Id and instead switch to hash . describe I dont have any more problems