D'oh, yeah that is better. You know, I actually had that and had expanded it because I was going to seq both the input and the result of the (+1), but punted on it and didn't switch back to the more compact format. -Ross On Jun 19, 2009, at 12:45 AM, Luke Palmer wrote:
On Thu, Jun 18, 2009 at 9:55 PM, Ross Mellgren
wrote: It looks offhand like you're not being strict enough when you put things back in the IORef, and so it's building up thunks of (+1)... With two slight mods:
go 0 = return () go n = do modifyIORef ior (+1) go (n-1)
-->
go 0 = return () go n = do modifyIORef ior (\ x -> let x' = x+1 in x `seq` x') go (n-1)
Just a slight prettification of that line:
modifyIORef ior ((1+) $!)
Or applied prefix if you prefer. Prefix ($!) has the nice interpretation as the HOF that makes its argument into a strict function.
Luke