[Haskell-cafe] Memory Management and Lists
Christopher Howard
ch.howard at zoho.com
Mon Jul 11 15:01:24 UTC 2016
-- I'm a bit embarrassed of this code because I haven't yet optimized
-- the 'stamp' algorithm for reduced number of matrix operations. But
-- even in this state I should think the memory requirements shouldn't
-- exceed 1MB while generating the nth Matrix, unless Matrix n-1, n-2,
-- etc. are being preserved in memory unnecessarily.
-- Monad Stack
type StateReader s c a = StateT s (Reader c) a
evalStateReader m s c = (runReader (evalStateT m s)) c
-- Helper function
type Point = (Float, Float)
type Metric = Point -> Point -> Float
euclidean :: Metric
euclidean (x1, y1) (x2, y2) = sqrt ((x2 - x1)**2 + (y2 - y1)**2)
-- monadic function. haven't had chance yet to optimize algorithm to
-- reduce number of matrix operations
stamp = do radius <- ask
(oMatrix, walk) <- get
(wX, wY) <- (return . head) walk
let nMatrix = matrix (nrows oMatrix) (ncols oMatrix)
(\(x, y) -> let (x', y') = (fromIntegral x, fromIntegral y)
in if euclidean (x', y') (wX, wY) > radius
then getElem x y oMatrix
else getElem x y oMatrix + 1)
in put (nMatrix, tail walk) >> get
-- sequences and gathers results as list
stampingStates initMx radius walk =
map fst $ evalStateReader (sequence (repeat stamp)) (initMx, walk) radius
-- Some quick experimentation code. h is the list
h = stampingStates initMx radius walk'
where initMx = zero 250 250
radius = 40
walk' = walk 40 (125, 125) (mkStdGen 31415)
-- get 2001st Matrix and convert to Gloss Picture, employing
-- some color interpretation code
intensityG = let mx = head (drop 2000 h)
in toImage mx (lightnessInt 272 (minMax mx))
On 07/10/2016 10:30 AM, Tom Ellis wrote:
> On Sun, Jul 10, 2016 at 07:41:31AM -0800, Christopher Howard wrote:
>> issue: a Matrix itself should only be, I'm guessing, somewhere around
>> 100KB. But instead I'm maxing out the 3GB of RAM on my old T60 laptop.
>> Maybe I'm generating list elements (Matrices) a lot faster than memory
>> management is releasing them...?
>
> You have almost certainly got a space leak. Can you post your code?
> _______________________________________________
> Haskell-Cafe mailing list
> To (un)subscribe, modify options or view archives go to:
> http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe
> Only members subscribed via the mailman list are allowed to post.
>
--
http://qlfiles.net
To protect my privacy, please use PGP encryption. It's free and easy
to use! My public key ID is 0x340EA95A (pgp.mit.edu).
More information about the Haskell-Cafe
mailing list