--- palin.parfromstring.hs	2019-11-06 23:40:12.648324958 +0100
+++ palin.parfromstringtostring.hs	2019-11-06 23:39:42.279920483 +0100
@@ -129,5 +129,5 @@
               cases <- replicateM n getLine
               let strategy = parBuffer cap rdeepseq
                   answers  = map (palindrome.fromString) cases `using` strategy
-               in mapM_ (putStrLn.toString) answers
-  where palindrome c = runST $ nextPalindrome c :: Vec.Vector Digit
+               in mapM_ putStrLn answers
+  where palindrome c = toString (runST $ nextPalindrome c :: Vec.Vector Digit)