rl:
replicate :: Int -> a -> New a replicate n x = Generic.New.unstream (Fusion.Stream.replicate n x)
and then either
Mutable.run (replicate n x)
to get a mutable vector or
new (replicate n x)
Hmm, but here 'a' is pure. I don't think he wants newWith :: (PrimMonad m, MVector v a) => Int -> a -> m (v (PrimState m) a) but more: newWithM :: (PrimMonad m, MVector v a) => Int -> m a -> m (v (PrimState m) a)
to get an immutable one. You could also chain operations on New, including monadic ones:
v <- Mutable.run $ Generic.New.transform (Fusion.Stream.Monadic.mapM f) $ replicate n x
Oh, that's interesting. But what if we want to fill directly with the monadic action? We wouldn't mapM (const a) $ replicate n undefined So how do we best do a fusible, e.g.: replicateM :: G.Vector v a => Int -> IO a -> IO (v a) -- Don