Thanks to Erik's help testing preview versions I've now released Hoogle 4.1.4 that sets the file creation mask appropriately.
Shouldn't data like this really go in /var rather than /usr ? To quote Wikipedia [1]: "/var/: Variable files—files whose content is expected to continually change during normal operation of the system—such as logs, spool files, and temporary e-mail files."
The Hoogle databases are expected to change very rarely - most users will install them when they install Hoogle. A small number will update them occasionally as the packages update. I'm using the Cabal datadir to store the databases, but does Cabal provide a more sensible place to put them? As a Windows user, I'm happy to defer to what Posix system users want. Thanks, Neil