bauertim:
I have a program that is currently blowing out the stack, Stack space overflow: current size 8388608 bytes. Use `+RTS -Ksize' to increase it. I am pretty sure I get to the end of the computation that increments various statistic counters (lazily?) and only when I go to print them out at the end, do things fail.
I have state monad transformer (StateT) that is keeping the counters among other things. The counters are stored in a pair within a larger data structure.
data AState s a = AS { ... asStats :: (Int,Int) ... }
I would always, always write this as: data AState s a = AS { ... , asStatsX, asStatsY :: !Int , ... } and compile with: ghc -O2 -funbox-strict-fields Simple heuristic: unless otherwise specified, atomic types should always be strict fields. -- Don