On 08/21/12 09:19, felipe zapata wrote: > Hi Haskellers, > > I have been playing with the Repa functions and trying the > Repa-examples. In order to gain experience with the Repa functions I > have written some small linear algebra utilities and import this module > to a bigger project. In the beginning of my project I used the mmultP > function from the repa-examples to calculate a big matrix, therefore I > have and array of type: > > > arr :: Monad m => m (Array U DIM2 Double) > > > Then I carried this array in a lot of functions which become Monadic > function and then it is necessary to introduce the monadic machinery for > manipulating this functions . The Question is then if there is the > possibility to work with a pure function in place of the monadic version? > > There is something like a runRepa function? > > runRepa :: Monad m => m (Array U DIM2 Double) - > Array U DIM2 Double > > > or could I used the unsafePerformIO function ? > > > or the evaluation of the parallel arrays must be postponed until the > Repa.Array is called in the main function?
When this change was introduced (there wasn't always the arbitrary monad m around everything), I remember I just wrapped my one big repa function in the identity monad and it worked fine. For example, -- Grid.hs import Control.Monad.Identity (Identity) ... zoom :: Values3D -> ScaleFactor -> Identity Values3D -- Main.hs import Control.Monad.Identity (runIdentity) ... let output = runIdentity $ zoom dbl_data zoom_factor This gives you the warm/fuzzy of knowing that the function is pure, but I think I eventually just let it run in IO to avoid introducing mtl as a dependency. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
