[Haskell-cafe] space leak?

[Massimiliano Gubinelli]

> ( these two lines are just to fool the gmane post algorithm which 
>   complains for top-posting....)


Hi,
 i'm learning Haskell and trying to use the HPDF 1.2 library I've come
 across some large memory  consumption for which I do not understand
 the origin. I've tried heap profiling but without much  success.
This is my code 


> module Main where

> import Control.Monad.State
> import Graphics.PDF 

> data Opcodes = Rect | Ship  deriving (Show)

> doPage (Rect:ops) = do
>      stroke $! Rectangle 10.0 10.0  10.0 10.0
>      doPage ops       

> doPage l = return l

> doOps [] = return ()

> doOps (Ship:ops) = {-# SCC "OPSHIP" #-}  do  
>     p <- addPage Nothing
>     ops' <- drawWithPage p $! do 
>               strokeColor red
>               applyMatrix $ (translate 72.0 72.0)
>               doPage ops  
>     doOps ops'

> doOps (op:_) = error ("unexpected " ++ show op)

> testpdf =  do
>    let ops = concat $ replicate 100 (Ship : (replicate 1000 Rect )) 
>        pageRect = PDFRect 0 0 
>                           (floor $ 21.0/2.54*72.0) (floor $ 29.7/2.54*72.0)
>    runPdf "test1.pdf" (standardDocInfo { author=toPDFString "mgubi", 
>                                          compressed = False}) 
>            pageRect $ doOps ops


> testpdf' = do  
>    let pageRect = PDFRect 0 0 
>                   (floor $ 21.0/2.54*72.0) (floor $ 29.7/2.54*72.0)
>    runPdf "full.pdf" (standardDocInfo { author=toPDFString "mgubi", 
>                                         compressed = False}) 
>             pageRect $ sequence_ $ foldM f [] $ replicate 100 $ 
>                 (\p -> sequence_ $ replicate 1000 $ 
>                           drawWithPage p $ stroke $ 
>                                Rectangle 0.0 0.0 10.0 10.0)
>             where f ps acts = do
>                         p <- addPage Nothing
>                         acts p    
>                         return $ p:ps

> main = testpdf


now, if I run testpdf' then memory profile is very low and everything
is as expected while if I run testpdf  then the profile grows up to
80MB and more. This is the stripped down version of the original
program  (which is a DVI interpreter) so there I will have also some
StateT and more complicated opcodes. I would  like to know what is
wrong with the above code. Could someone help me? 

thanks,

Massimiliano Gubinelli