[Haskell-cafe] Monads as control structures?

Björn Bringert bringert at cs.chalmers.se
Thu Oct 27 12:07:17 EDT 2005

Creighton Hogg wrote:
> Hi,
> so I'm a newbie getting used to Haskell.  I'm writing some 
> simple things like genetic algorithms in it for practice, 
> and I keep coming across something that really bugs me:  
> are there any standard libraries that allow you to 
> do imperative style for or while loops using monads to keep 
> track of state?
> I know there's things like "until", but honestly that's not 
> quite what I'm looking for.  
> I just think there should be a simple way to say "execute 
> this block of code 10 times" without having to wrap it up in 
> recursion.  
> Haskell seems to me to be a very powerful language, and it 
> looks like it should be possible to define control 
> structures such as for loops using monads.

Could Control.Monad.replicateM or Control.Monad.replicateM_ be what you 
are looking for?


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