After a quick look at your code, I very much doubt that. You use the mysql-simple package, which in turn uses the mysql package, which in turn uses the native mysqlclient library. My (and probably most people's) reaction here is: It is much, much more probable that either

   a) you use the package/library incorrectly

or

   b) the package/library has a bug

than that you have discovered a compiler bug for otherwise farily trivial code. Your best bet is to either rip out the mysql dependencies and still reproduce the bug or issue a bug report at e.g. https://github.com/paul-rouse/mysql-simple/issues.

Note that I'm not saying that GHC is bug-free, it is just a question where people will probably like to spend their time on. Given the fact that there are tons of buggy packages/libraries with questionable quality out there, it is basically *your* onus to show that your problem is GHC's fault.

Just my 2c...