Data commit

Task/Constrained-random-points-on-a-circle/Haskell/constrained-random-points-on-a-circle.hs

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+import Data.List
+import Control.Monad
+import Control.Arrow
+import Rosetta.Knuthshuffle
+
+task = do
+  let blanco = replicate (31*31) "  "
+      cs = sequence [[-15,-14..15],[-15,-14..15]] :: [[Int]]
+      constraint = uncurry(&&).((<= 15*15) &&& (10*10 <=)). sum. map (join (*))
+-- select and randomize all circle points
+  pts <- knuthShuffle $ filter constraint cs
+-- 'paint' first 100 randomized circle points on canvas
+  let canvas = foldl (\cs [x,y] -> replaceAt (31*(x+15)+y+15) "/ " cs ) blanco (take 100 pts)
+-- show canvas
+  mapM_ (putStrLn.concat). takeWhile(not.null). unfoldr (Just . splitAt 31) $ canvas