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POHow do you save a tree data structure to binary file in Haskell
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  1. POHow do you save a tree data structure to binary file in Haskell
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    copied!<p>I'm trying to save a simple (but quite big) Tree structure into a binary file using Haskell. The structure looks something like this:<pre> -- For simplicity assume each Node has only 4 childs data Tree = Node [Tree] | Leaf [Int] </pre> And here is how I need the data look on disk:</p> <ol> <li>Each node starts with four 32-bit offsets to it's children, then follow the childs.</li> <li>I don't care much about the leafs, let's say it's just n consecutive 32-bit numbers.</li> <li>For practival purposes I would need some node labels or some other additional data but right now I don't care about that much neither.</li> </ol> <p>It apears to me that Haskellers first choice when writing binary files is the Data.Binary.Put library. But with that I have a problem in the bullet #1. In particular, when I'm about to write a Node to a file, to write down the child offsets I need to know my current offset and the size of each child.</p> <p>This is not something that Data.Binary.Put provides so I thought this must be a perfect application of Monad transformers. But even though it sounds cool and functional, so far I have not been successfull with this approach.</p> <p>I asked two other questions that I thought would help me solve the problem <a href="https://stackoverflow.com/questions/4828902/why-wrapping-the-data-binary-put-monad-creates-a-memory-leak">here</a> and <a href="https://stackoverflow.com/questions/5019655/why-wrapping-the-data-binary-put-monad-creates-a-memory-leak-part-2">here</a>. I must say that each time I received very nice answers that helped me progress further but unfortunatelly I am still unable to solve the problem as a whole.</p> <p><a href="http://hpaste.org/44419/how_do_you_save_a_tree_data_st" rel="nofollow noreferrer">Here</a> is what I've got so far, it still leaks too much memory to be practical.</p> <p>I would love to have solution that uses such functional approach, but would be grateful for any other solution as well.</p>
 

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