
I faced the same problem in an RWS monad, where adding a print to the
evalRWS resolves the space leak. Obviously, it's not very elegant to
clutter the output. I tried the unsafeInterleaveIO (works sometimes),
seq/deepseq (works on Windows but not on Linux??), strictness annotations
(didn't seem to help at all?), but finally settled on using pipes/conduit.
It's remarkable how a streaming library is more practical than the
language's core feature - laziness.
On 14 July 2016 at 16:32, Matthew Bray
https://www.schoolofhaskell.com/user/edwardk/snippets/once
Cool trick :)
On Thu, 14 Jul 2016 at 08:56 Tom Ellis < tom-lists-haskell-cafe-2013@jaguarpaw.co.uk> wrote:
Yes, this is a very neat trick and very effective. (I couldn't acutally find it on Hoogle. Does anyone have a link?)
For deepseq also see the"Once trick". I'm surprised it's not quoted more often. In fact our would make sense to mention it in the deepseq docs.
On Wed, Jul 13, 2016, 21:32 David Feuer
wrote: You have to be careful with deepseq. Using it in the wrong place can lead to very bad performance. It's a big hammer. Its blow can sometimes be softened using the NF type from the nf package, but it's really not the right thing most of the time.
On Tue, Jul 12, 2016 at 11:56 PM, William Yager
wrote:
You probably want Control.DeepSeq. No extraneous work doing addition that way either.
Will
On Tue, Jul 12, 2016 at 11:28 PM, Christopher Howard < ch.howard@zoho.com
wrote:
After pondering this problem some more, I found a solution to the problem was to introduce strictness, not deep down in the
StateReader
monad, but rather at the top level, i.e., forcing evaluation of each Matrix as soon as it is pulled of the list of Matrices. I found I could do this simply by summing all the elements in each matrix and
the sum to std out. With this approach, i successfully run the full program and never even saw my memory performance graph move up.
I suppose there might be a way to do the same thing more efficiently with seq...?
On 07/12/2016 06:39 PM, Christopher Howard wrote: > I guess I was hesitating on posting the entire program source code in an > cafe email. I suppose I could send you a tarball, if you really wanted > it... > > Matrix is from Data.Matrix > > <
http://hackage.haskell.org/package/matrix-0.3.5.0/docs/Data-Matrix.html>.
> > It is hard to understand how thunks alone would explain it...
> would be at most 2000 thunks, right? Unless... Could there be a
On Thu, Jul 14, 2016 at 07:45:33AM +0000, Robin Palotai wrote: printing there thunk
> for every single call to getElem? That would be a lot of thunks! > > Somebody suggested adding some strictness here... could you elaborate on > that? I tried inserting seq, but I didn't really understand how I was > supposed to use it... >
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