import Data.Ratio
 
myEnumFromThen     :: (Fractional a) => a -> a -> [a]
myEnumFromThen n m = n `seq` m `seq` (n : myEnumFromThen m (m+m-n))
 
myEnumFromThenTo   :: (Ord a, Fractional a) => a -> a -> a -> [a]
myEnumFromThenTo e1 e2 e3
    = takeWhile predicate (myEnumFromThen e1 e2)
                                where
                                 predicate | e2 >= e1  = (<= e3)
                                           | otherwise = (>= e3)
 
main = do
    print $ (myEnumFromThenTo 1.3 1.6 2.8 :: [Float])
    print $ (myEnumFromThenTo 1.3 1.6 2.8 :: [Ratio Int])

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