Hi Bill, Very clever.
You are an inspiration. Michael --- On Sat, 8/14/10, Bill Atkins <watk...@alum.rpi.edu> wrote: From: Bill Atkins <watk...@alum.rpi.edu> Subject: Re: [Haskell-cafe] Unwrapping long lines in text files To: "michael rice" <nowg...@yahoo.com> Cc: "Felipe Lessa" <felipe.le...@gmail.com>, haskell-cafe@haskell.org Date: Saturday, August 14, 2010, 12:33 PM Try this one (http://gist.github.com/524460): import Data.Char maxLineLength :: Int maxLineLength = 72 trim :: String -> String trim = reverse . dropSpaces . reverse . dropSpaces where dropSpaces = dropWhile isSpace none :: (a -> Bool) -> [a] -> Bool none f = not . any f reverseBreak :: (a -> Bool) -> [a] -> ([a], [a]) reverseBreak f xs = (reverse before, reverse after) where (after, before) = break f $ reverse xs wrapLine :: String -> [String] wrapLine "" = [[]] wrapLine line | length line <= maxLineLength = [line] | none isSpace line = beforeMax : wrapLine afterMax | otherwise = beforeSpace : (wrapLine $ afterSpace ++ afterMax) where (beforeMax, afterMax) = splitAt maxLineLength line (beforeSpace, afterSpace) = reverseBreak isSpace beforeMax main :: IO () main = interact $ unlines . concatMap (map trim . wrapLine) . lines On Saturday Aug 14, 2010, at 9:41 AM, michael rice wrote: > Hi Filipe, Bill > > Your corrected version works, while the original didn't, but it still > produces incorrect > output: > > However mean your life is, meet it and live it: do not shun it and call > it hard names. Cultivate poverty like a garden herb, like sage. Do not t > rouble yourself much to get new things, whether clothes or friends. Thin > gs do not change, we change. Sell your clothes and keep your thoughts. G > od will see that you do want society. > Men have become the tools of their tools. > I know of no more encouraging fact than the unquestioned ability of a ma > n to elevate his life by conscious endeavor. > I once had a sparrow alight upon my shoulder for a moment, while I was h > oeing in a village garden, and I felt that I was more distinguished by t > hat circumstance that I should have been by any epaulet I could have wor > n. > -Thoreau > > I don't want to break lines in the middle of words and I want to retain the > original structure of the text with respect to blank lines between individual > quotes. THe only thing in the input text that should change are the lines > longer than 72 characters, and they should be reformatted to one or more > lines less than or equal to 72 characters. > > Michael > > --- On Sat, 8/14/10, Felipe Lessa <felipe.le...@gmail.com> wrote: > > From: Felipe Lessa <felipe.le...@gmail.com> > Subject: Re: [Haskell-cafe] Unwrapping long lines in text files > To: "Bill Atkins" <watk...@alum.rpi.edu> > Cc: "michael rice" <nowg...@yahoo.com>, haskell-cafe@haskell.org > Date: Saturday, August 14, 2010, 9:17 AM > > On Sat, Aug 14, 2010 at 9:59 AM, Bill Atkins <watk...@alum.rpi.edu> wrote: > > | otherwise = let (line, rest) = > >splitAt maxLineLength line in > > line : > >wrapLine rest > > I haven't tested myself, but does this work at all? If I am reading > it correctly, this is the same as > > let (foo, rest) = splitAt maxLineLength foo > in foo : wrapLine rest > > In other words, no mention of wrapLine's argument 'line', and a > recursive call that will bottom out and be the same as 'undefined' :). > GHC would warn you, though, if you used -Wall. That expression > should read: > > let (thisLine, rest) = splitAt maxLineLength line > in thisLine : wrapLine rest > > Cheers, > > -- > Felipe. >
_______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
