Re: [Haskell-beginners] Mapping inside State

Am 03/31/2014 10:42 PM, schrieb Chaddaï Fouché:

Le 31 mars 2014 18:07, "martin" mailto:martin.drautzburg@web.de> a écrit :

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Hello all,

I found myselft writing this ugly piece of code

silenceAll :: TI -> State (M.Map CH StringState,[DtzEvent]) TI silenceAll t =

Cut

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because I couldn't figure out how to map (silence t) over [0..6]. What is the standard way of doing this

As said, mapM_ is the standard way to do that . How could you have found this for yourself ? The recommended way would be to use hoogle to search for the type signature you wish : (Monad m) => (a -> m b) -> [a] -> m () mapM_ would be among the first results.

Thanks Ozgur and Chaddai, this works. Two more questions: (1) I had tried mapM, but this didn't work. I am having trouble to understand why the return type is m() and not m [a] (2) Hoogle is http://www.haskell.org/hoogle, right? I mean, it is a web thing, not something I use from the commandline?