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+{-# LANGUAGE Trustworthy #-}
+
+-- | Here we expose a MinList API that only allows elements
+-- to be inserted into a list if they are at least greater
+-- than an initial element the list is created with.
+module SafeLang07_A (
+ MinList,
+ newMinList,
+ insertMinList,
+ printIntMinList
+ ) where
+
+data MinList a = MinList a [a]
+
+newMinList :: Ord a => a -> MinList a
+newMinList n = MinList n []
+
+insertMinList :: Ord a => MinList a -> a -> MinList a
+insertMinList s@(MinList m xs) n | n > m = MinList m (n:xs)
+ | otherwise = s
+
+printIntMinList :: MinList Int -> IO ()
+printIntMinList (MinList min xs) = putStrLn $ "MinList Int :: MinList " ++ show min ++ " " ++ show xs
+