Re, Joseph (IT) wrote:
At this point I'm out of ideas, so I was hoping someone could identify something stupid I've done (I'm still novice of FP in general, let alone for high performance) or direct me to a guide,website,paper,library, or some other form of help.
Two ideas about your aproaches: (1) try to avoid explicit recursion by using some standard library functions instead. it's easier (once you learned the library) and may be faster (since the library may be written in a easy to optimize style). (2) try lazy ByteStrings, they should be faster. http://www.cse.unsw.edu.au/~dons/fps.html As an example, sorting of the individual lines of a csv files by key. csv parses the csv format, uncsv produces it. these functions can't handle '=' in the key or ',' in the key or value. treesort sorts by inserting stuff into a map and removing it in ascending order:
import System.Environment import qualified Data.ByteString.Lazy.Char8 as B import qualified Data.Map as Map import Control.Arrow (second)
csv = (map $ map $ second B.tail . B.break (== '=')) . (map $ B.split ',') . (B.split '\n')
uncsv = (B.join $ B.pack "\n") . (map $ B.join $ B.pack ",") . (map $ map $ \(key, val) -> B.concat [key, B.pack "=", val])
treesort = Map.toAscList . Map.fromList
main = B.interact $ uncsv . map treesort . csv
Tillmann