[Haskell-beginners] [IO String] to IO [String]

[Lyndon Maydwell]

Interact should be able to handle line-by-line interaction as per this
example, it should even be able to handle the exit case thanks to laziness:

> main :: IO ()
> main = interact (unlines . map reverse . lines . untilexit)
>
> untilexit :: String -> String
> untilexit ('e':'x':'i':'t':_) = []
> untilexit (c:t)               = c : untilexit t
> untilexit []                  = []

There will be a lot of things that it won't be able to do however.


On Mon, Apr 1, 2013 at 5:49 AM, Ovidiu D <ovidiudeac at gmail.com> wrote:

> My problem with interact was that it doesn't give me the line when the
> user hits enter but instead it gives me all the lines at once when stdin is
> closed (unless I did something wrong)
>
> The other problem is that I want to stop the command processing when the
> user types the command "exit" and it seems interact can't do that.
>
>
> On Sun, Mar 31, 2013 at 2:52 PM, Lyndon Maydwell <maydwell at gmail.com>wrote:
>
>> Depending on what you're doing with the lines, it may be worth checking
>> out the `interact` function as well :-)
>>
>>
>> On Sun, Mar 31, 2013 at 7:42 PM, Kim-Ee Yeoh <ky3 at atamo.com> wrote:
>>
>>> On Sun, Mar 31, 2013 at 5:19 PM, Ovidiu D <ovidiudeac at gmail.com> wrote:
>>> > I would like to make this function to have the signature
>>> > f : IO [String]
>>> > ...such that I can get rid of the IO monad and pass the pure string
>>> list to
>>> > the processing function.
>>>
>>> You could use:
>>>
>>> getContents >>= lines :: IO [String]
>>>
>>> -- Kim-Ee
>>>
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