Travis Erdman wrote:
The driver of my algorithm looks like this:
foldl' processfn nullarray (take arg infinitelist)
where processfn takes an array and the next set of inputs, processes, and delivers a new updated array (using the Data.Vector library).
Apparently, I have a space leak ... the "maximum residency" varies linearly with the size of "arg" supplied, garbage collection consumes ~75% of CPU time, and, if the arg is too big, the whole thing crashes with an out of memory error. The algorithm should operate in constant space.
As you can see, I'm using a strict left-fold and also have made the accumulating array strict in the processfn definition with a bang pattern. So, I'm sort of at a loss as to how to resolve this.
I take it that size of the array does not depend on arg ? Apparently, despite your attempts to force evaluation, the array still contains many unevaluated expressions. Documentation for the vector pacakge reveals that Data.Vector is a *boxed* array, i.e. the entries are only evaluated on demand, so that's where the unevaluated expressions linger around. Unless you need the extra laziness - which you probably don't, given how you've structured your algorithm - you might want to switch to Data.Vector.Unboxed or Data.Vector.Storable . Regards, Heinrich Apfelmus -- http://apfelmus.nfshost.com