29 lines
901 B
Haskell
29 lines
901 B
Haskell
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module Conway
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( Index(..)
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, update
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)
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where
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import Data.List
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import qualified Data.Vector.Sized as V
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import Data.Map (Map)
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import qualified Data.Map as M
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import Data.Set (Set)
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import qualified Data.Set as S
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class Index i where
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neighbours :: i -> [i]
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addIndex :: i -> i -> i
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counts :: Ord a => [a] -> Map a Int
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counts = M.fromList . map (\xs -> (head xs, length xs)) . group . sort
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neighbourCounts :: (Index i, Ord i) => Set i -> Map i Int
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neighbourCounts = counts . concatMap neighbours . S.elems
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update :: (Index i, Ord i) => (Int -> Bool) -> (Int -> Bool) -> Set i -> Set i
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update create destroy old = M.keysSet $ M.filterWithKey shouldLive $ M.fromSet (flip (M.findWithDefault 0) nCounts) indices
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where nCounts = neighbourCounts old
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indices = S.union old $ M.keysSet nCounts
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shouldLive ix n = if S.notMember ix old then create n else not $ destroy n
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