[Haskell-cafe] Data.List / Map: simple serialization?

Dmitri O.Kondratiev dokondr at gmail.com
Thu Jun 9 17:30:31 CEST 2011

On Thu, Jun 9, 2011 at 7:23 PM, Max Bolingbroke
<batterseapower at hotmail.com>wrote:

> Hi Dmitri,
> On 9 June 2011 09:13, Dmitri O.Kondratiev <dokondr at gmail.com> wrote:
> > I wonder how Haskell will distribute memory between the buffer for
> > sequential element access (list elements, map tree nodes) and memory for
> > computation while reading in list, Data.Map from file?
> Your list only has 30,000 elements. From the description of the
> problem, you traverse the list several times, so GHC will create an
> in-memory link list that persists for the duration of all the
> traversals. This is OK, because the number of elements in the list is
> small.
> For the construction of the Map, it sounds like in the worst case you
> will have 30,000*30,000 = 900,000,000 elements in the Map, which you
> may not want to keep in memory. Assuming "show", "read" and list
> creation are lazy enough, and as long as you use the Map linearly GHC
> should be able to GC parts of it to keep the working set small. You
> should experiment and see what happens.
> My advice is just write the program the simple way (with show and
> read, and not worrying about memory) and see what happens. If it turns
> out that it uses too much memory you can come back to the list with
> your problematic program and ask for advice.
> Max

Yes, that's what I will try first - simple serialization with show and
read, not worrying about memory.
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