On Tue, 2011-02-15 at 14:06 -0500, Brandon S Allbery KF8NH wrote:
entirely consumed that the descriptor gets closed. Is hGetContents responsible for closing the descriptor? Or is it the garbage collector? Who closes the descriptor when the contents are read? Looking at hGetContents function
The garbage collector closes the handle, as I understand it.
The handle is actually closed as soon as you read all the way to the end of the file. However, because reading is done as a side effect of forcing a lazy, supposedly-pure value, it's hard to predict when that will happen, and apprently unrelated changes in a different part of the program can cause it to never happen and cause you to leak file handles. In a way, it's analogous to the situation with garbage collection and closing file handles in finalizers; but the details are different and the unpredictable file closing comes from lazy evaluation rather than garbage collection. -- Chris Smith