[Haskell-cafe] Bulletproof resource management

[Henning Thielemann]

On Fri, 8 Oct 2010, Florian Weimer wrote:

> At least in my experience, in order to get proper resource management
> for things like file or database handles, you need both a close
> operation and a finalizer registered with the garbage collector.  The
> former is needed so that you can create resources faster than the
> garbage collector freeing them.  The latter is a safety net in cases
> where proper resource management is not follwoed (perhaps in GHCi).
> When the explicit close operation or the finalizer has been invoked,
> the object must somehow be disabled, so that further operations on it
> fail (otherwise, you might dereference a dangling pointer).

Some open/close pairs have corresponding 'with' functions, that are 
implemented using Exception.bracket. You can also use them within GHCi. I 
think using both manual resource deallocation and finalizers makes 
everything more complicated and more unreliable.