27 lines
862 B
Haskell
27 lines
862 B
Haskell
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import Control.Monad (mapM_)
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import Data.List (partition)
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-- | Split off any nums that satisfy the relation and return the split and the rest in a tuple
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splitOffRelatedNums :: (Integer -> Integer -> Bool) -> [Integer] -> ([Integer],[Integer])
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splitOffRelatedNums relation nums = partition (relation x) nums
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where
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x = head nums
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-- | Split off equivalence groups until there are no more that satisfy the condition
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getEquivalenceClasses :: (Integer -> Integer -> Bool) -> [Integer] -> [[Integer]]
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getEquivalenceClasses relation nums
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= case nums of
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[] -> []
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nums -> x : getEquivalenceClasses relation xs
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where
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(x,xs) = splitOffRelatedNums relation nums
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main :: IO ()
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main = do
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let
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setA = [1..7]
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relation :: Integer -> Integer -> Bool
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relation x y = (x - y) `mod` 3 == 0
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mapM_ print $ getEquivalenceClasses relation setA
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