[Haskell-beginners] Ignoring the result of a monadic computation

[Tim Baumgartner]

Hi Haskellers,

this was my first post and I'm thankful and really impressed how many qualified answers I got. I've been learning Haskell only for a short time but I'm really fascinated how mathematical and expressive a programming language can be (I usually code Java). Recently I read a blog post, with a function

map (length &&& head) . group

that was much shorter and more elegant than the corresponding Python code. That was the main reason for me to try to write my own code in a single line without any lambda expressions.

Regards
Tim


-------- Original-Nachricht --------
> Datum: Fri, 19 Nov 2010 07:56:02 +0100
> Von: "Tim Baumgartner" <jongleur0815 at gmx.de>
> An: beginners at haskell.org
> Betreff: [Haskell-beginners] Ignoring the result of a monadic computation

> Hi,
> 
> while learning about monads, I had something like
> 
> do
>    line <- getLine
>    something
>    putStrLn line
> 
> and I wondered if I could write it in one line, without naming of
> parameters.
> I finally came up with
> 
> getLine >>= ignore something >>= putStrLn
> 
> using
> ignore :: Monad m => m a -> b -> m b
> ignore m a = m >> return a
> 
> I'm satisfied with this solution but searching hoogle I didn't find a
> standard function for my ignore. Am I missing something?
> 
> Cheers,
> Tim
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