2008/9/30 wman <666wman@gmail.com>:
I got asked how to do one particular thing in excel, which led to discssion with "our local MSOffice expert". During the discussion I stated that's it too much of a PITA and that I'd rather write a script. Long story short, I promised him a one-liner to "show the power and beauty of Haskell".
I got the csv package from hackage, modified the parseCSVFromFile so it's returns IO CSV rather than IO (Either ParseError CSV), and finished with following code
(writeFile "output.csv") =<< (liftM printCSV $ liftM (map updateLine) $ parseCSVFromFile "input.csv")
Is there room for improvement ? Could it still be made into one-liner without modifying the csv module (and without resorting to case parseCSVFromFile "input.csv" of { Left _ -> []; Right x -> x} kind of tricks) ?
I have good news for you: either :: (b ->c) (a -> c) (Either b a) -> c That type signature is from memory, but you get the idea. You pass in two functions - one to deal with the Left and the other to deal with the Right, and it sorts out your result for you. Cheers, D -- Dougal Stanton dougal@dougalstanton.net // http://www.dougalstanton.net