Mon, 09 Apr 2001 09:39:05 +0200
Use may write:
main = do
putStr "Filename plz: "
file <- getLine
content <- readFile file
let linesWithNo = map (\(lineNo, s) -> show lineNo ++ ": " ++ s) (zip
[1..] (lines content))
mapM putStrLn linesWithNo
Filename plz: lines.hs
1: main = do
2: putStr "Filename plz: "
3: file <- getLine
4: content <- readFile file
5: let linesWithNo = map (\(lineNo, s) -> show lineNo ++ ": " ++ s)
(zip [1..] (lines content))
6: mapM putStrLn linesWithNo
mapple apple schrieb:
> Hi everyone,
> I'm not sure this is the place to ask, coz I hvn't join your mailing
> list. But anyway ..
> Here's the case .. does anybody know 'bout IO recursion?
> ie. We've a file and we want to put a numberline
> 1: 'first line'
> 2: 'second line'
> until n, where n is the last line
> I know how to convert a file into a huge string using 'readFile'
> and I'm using the 'lines function' in the prelude.
> That means i have a huge string like "\nHi mate\nHow r u?"
> using the helper function 'lines' i can do that by saying :
> main :: IO ()
> main = do
> putStr "Filename plz: "
> file <- getLine
> content <- readFile file
> putStr ("1: " ++ read (show (head (lines content))))
> and so on
> that's not recursive function and will not work for all cases.
> So please .. if anyone knows how to do those things, let me know.
> one more thing, does anybody know how to join the mailing list??
> mapple apple
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