[Haskell-beginners] lazy IO by example

[Tim Baumgartner]

2011/2/5 Dean Herington <heringtonlacey at mindspring.com>

> In your simplified example, it suffices to wrap unsafeInterleaveIO around
> (mapM content ds).  In a more realistic case, you'd need to add some
> `unsafeInterleaveIO`s in `files` and `directories`, too.
>

Thanks a lot! Now it was easy to write a lazy findFiles.
Would one have to write down a lot in order to see "on paper" why the
original example was not lazy? If I coud do this, I might run into fewer
problems in the future.



> Dean
>
> P.S. You might also want to look into iteratees, which accomplish a similar
> goal in a more robust way.
>

Yes, I already looked over the article in Monad reader #16. But then I
thaught I will first gain more understanding of the traditional way and then
return to iteratees.


Regards
Tim
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