BTW, this is a case where it may be more convenient to use forM:
forM ps $ \pix -> do
particle <- read_grid g pix
return $ fn particle
(untested...)
forM is just another way of saying (flip mapM).
/ Emil
Andrew Coppin skrev:
colour_grid :: (Particle -> IO ()) -> Grid ph -> IO ()
colour_grid fn g = sequence_ $ runST $ do
ps <- grid_coords g
mapM
(\pix -> do
particle <- read_grid g pix
return $ fn particle
)
ps
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...
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