Hi, well, rgbliste has type: *Main> :t rgbliste rgbliste :: [(Integer, Integer, Integer)] unless you have farbliste as well, in which case it is: *Main> :t rgbliste rgbliste :: [(GHC.Word.Word16, GHC.Word.Word16, GHC.Word.Word16)] Of course, with NoMonomorphismRestriction, the type becomes: *Main> :t rgbliste rgbliste :: Integral t => [(t, t, t)] So you restrict rgbliste to Word16's, once you have farbliste. ... I have not checked that the modulo calculations are actually correct modulo Word16, or modulo Integer... Gruss, Christian * Andreas Abel <andreas.abel@ifi.lmu.de> [16.07.2012 17:28]:
Today a student came to me with a piece of code that worked it executed by itself, but produced different result in the context of his larger problem. We cut down the example to the following:
import Graphics.UI.Gtk
-- should produce [(26471,0,65535),... rgbliste = (map (\ i -> let rb = 5 * (mod (mod 181935629 (4534+i)) 100)-250+128 in let gb = 5 * (mod (mod 128872693 (5148+i)) 100)-250+128 in let bb = 5 * (mod (mod 140302469 (7578+i)) 100)-250+128 in let r = min 255 $ max 0 rb in let g = min 255 $ max 0 gb in let b = min 255 $ max 0 bb in (r*257,g*257,b*257)) [0..])
--farbliste = map (\ (r,g,b) -> Color r g b) rgbliste
main :: IO () main = do print $ head rgbliste
If you run it, it prints (26471,0,65535). If you uncomment the def. of farbliste, it prints (44461,65535,65535).
I was surprised. What is going on?
Cheers, Andreas
-- Andreas Abel <>< Du bist der geliebte Mensch.
Theoretical Computer Science, University of Munich Oettingenstr. 67, D-80538 Munich, GERMANY
andreas.abel@ifi.lmu.de http://www2.tcs.ifi.lmu.de/~abel/
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