+-- | The 'isInfixOf' function takes two lists and returns 'True'
+-- iff the first list is contained, wholly and intact,
+-- anywhere within the second.
+--
+-- Example:
+--
+-- >isInfixOf "Haskell" "I really like Haskell." -> True
+-- >isInfixOf "Ial" "I really like Haskell." -> False
+isInfixOf :: (Eq a) => [a] -> [a] -> Bool
+isInfixOf needle haystack = any (isPrefixOf needle) (tails haystack)
+