[Haskell-beginners] Getting a specified number of lines from stdin

[Henk-Jan van Tuyl]

On Sun, 06 Mar 2016 11:38:47 +0100, Nicolaas du Preez  
<njdupreez at yahoo.com> wrote:
:
> Why does
>
>     liftM (take 5) $ sequence $ repeat getLine
>
> not stop at reading only 5 lines from stdin but keeps on reading more?
>
> What I’m really trying to achieve is to get input from the user until
> an empty line is read with the code below.  But this doesn’t work
> as I expected, similar to the above.
>
>     liftM (takeWhile (/= "")) $ sequence $ repeat getLine
:

It seems that
   sequence $ repeat getLine
is too strict for this; to get five lines, you could use:
   sequence $ replicate 5 getLine
. To read until the first empty line, I would write something in  
do-notation.

Regards,
Henk-Jan van Tuyl


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