On 3/6/07, Dave@haskell.org
Does the following code increase the level of recursion once for each input line or is the recursive construct converted to an iteration?
Thanks, Dave Feustel
main :: IO () main = do line <- getLine processIt line main
processIt :: String -> IO () processIt s = do print (length s)
Dave, I would imagine it does not, but I will let somebody more knowledgeable tell you for sure. My thought, though, is that if this is your whole code and not a simplified version (eg, one that terminates on certain input), then you could consider using the Prelude's 'interact'[1] function, which performs a transformation on standard input. In your case, the code would simplify to: main = interact (unlines . map (show . length) . lines) The unlines/lines combo breaks up the whole input into a list of lines of input, and the (show . length) is the heart of your 'processIt' function. Alternately, you could also use something like: main = getContents >>= mapM_ processIt . lines Which takes everything from standard in, splits it up into lines, and then performs processIt for each line. [1] http://haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html#v%3Ainte... Bryan