[Haskell-cafe] mapM for vectors

Don Stewart dons at galois.com
Thu Apr 8 16:01:06 EDT 2010


alexey.skladnoy:
> Hello
> 
> I found that there is no monadic map for vector. It's possible to define to 
> define such map using conversion to list, but I suppose it's not efficient. I 
> didn't make any measurements.
> 
> > mapM' :: Monad m => (a -> m b) -> V.Vector a -> m (V.Vector b)
> > mapM' f = return . V.fromList <=< mapM f . V.toList
> 
> Any suggestions about implementation of such function? 
> Specifically I want to use Random monad.
> 


There's a tutorial here on usving vectors,

    http://haskell.org/haskellwiki/Numeric_Haskell:_A_Vector_Tutorial#Random_numbers

mapM is available via Fusion.Stream.Monadic.mapM

-- Don



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