Re: [Haskell-cafe] mapM for vectors

Don Stewart schrieb:

alexey.skladnoy:

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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.

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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_num...

mapM is available via Fusion.Stream.Monadic.mapM

But can it be efficient? It must handle cases like m = [] and thus creation of the (V.Vector b) result means a lot of copying, right?