I'm using Repa to process a ton of MRI data. The basic process is, * Read in the data * Create a big 'ol data structure (grid) from it * Compute the output in parallel using 'traverse' * Write the output to file However, during the last step, I'm getting, $ ./bin/spline3 +RTS -N4 spline3: output.txt: hFlush: illegal operation (handle is closed) Here's the entirety of my Main.hs:

module Main where

import Data.Array.Repa ( DIM3, Z(..), (:.)(..), )

import Values import Grid(make_grid, zoom)

mri_shape :: DIM3 mri_shape = (Z :. 256 :. 256 :. 109)

main :: IO () main = do mridata <- read_values_3d mri_shape "./data/mridata.txt" let g = make_grid 1 mridata let output = zoom g 1 write_values_1d output "output.txt"

And the two functions used from the Values module,

type Values1D = Array DIM1 Double type Values3D = Array DIM3 Double

read_values_1d :: FilePath -> IO Values1D read_values_1d path = readVectorFromTextFile path

read_values_3d :: DIM3 -> FilePath -> IO Values3D read_values_3d sh path = do one_d <- read_values_1d path return $ reshape sh one_d

write_values_1d :: Values3D -> FilePath -> IO () write_values_1d v3d path = do let size3d = size $ extent v3d let shape1d = (Z :. size3d) let v1d = reshape shape1d v3d writeVectorToTextFile v1d path

Am I doing something obviously wrong here? It takes about 45 minutes to run up to the point of failure, so I haven't attempted much trial & error. Packages: * ghc-7.2.1 * repa-2.1.1.6 * repa-io-2.1.0.1