[Haskell-cafe] Why doesn't this work?

Andrew Coppin andrewcoppin at btinternet.com
Sun Aug 24 09:25:08 EDT 2008

colour_grid :: (Particle -> IO ()) -> Grid ph -> IO ()
colour_grid fn g = sequence_ $ runST $ do
  ps <- grid_coords g

    (\pix -> do
      particle <- read_grid g pix
      return $ fn particle

When I attempt to run this, GHCi just gives me a very cryptic type 
checker error. I can't figure out what's wrong here. As far as I can 
tell, this should run...

More information about the Haskell-Cafe mailing list