Add remaining haskell book exercises

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diff --git a/Haskell-book/26/Exercises/src/Exercises.hs b/Haskell-book/26/Exercises/src/Exercises.hs
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+module Exercises where
+
+import Control.Monad.IO.Class (liftIO)
+import Control.Monad.Trans.Class (lift)
+import Control.Monad.Trans.Reader (Reader(..), ReaderT(..), runReader, runReaderT)
+import Control.Monad.Trans.State (StateT(..))
+import Data.Functor.Identity (Identity(..))
+
+-- 1. rDec is a function that should get its argument in the context of
+-- Reader and return a value decremented by one.
+--
+-- Note that “Reader” from transformers is ReaderT of Identity and
+-- that runReader is a convenience function throwing away the
+-- meaningless structure for you. Play with runReaderT if you like.
+rDec :: Num a => Reader a a
+rDec = ReaderT $ dec
+    where dec :: Num a => a -> Identity a
+          dec = return . (flip (-) 1)
+
+-- 2. Once you have an rDec that works, make it and any inner lamb-
+-- das pointfree if that’s not already the case.
+
+
+-- 3. rShow is show, but in Reader.
+rShow :: Show a => Reader a String
+rShow = ReaderT $ toString
+    where toString = return . show
+
+-- 4. Once you have an rShow that works, make it pointfree.
+
+
+-- 5. rPrintAndInc will first print the input with a greeting, then return
+-- the input incremented by one.
+rPrintAndInc :: (Num a, Show a) => ReaderT a IO a
+rPrintAndInc = ReaderT print
+    where print x = do
+            liftIO $ putStrLn $ "Hi: " ++ show x
+            return $ x + 1
+
+-- Prelude> runReaderT rPrintAndInc 1
+-- Hi: 1
+-- 2
+-- Prelude> traverse (runReaderT rPrintAndInc) [1..10]
+-- Hi: 1
+-- Hi: 2
+-- Hi: 3
+-- Hi: 4
+-- Hi: 5
+-- Hi: 6
+-- Hi: 7
+-- Hi: 8
+-- Hi: 9
+-- Hi: 10
+-- [2,3,4,5,6,7,8,9,10,11]
+
+
+-- 6. sPrintIncAccum first prints the input with a greeting, then puts
+-- the incremented input as the new state, and returns the original
+-- input as a String.
+sPrintIncAccum :: (Num a, Show a) => StateT a IO String
+sPrintIncAccum = StateT print
+    where print x = do
+            liftIO $ putStrLn $ "Hi: " ++ show x
+            return $ (show x, x + 1)
+
+-- Prelude> runStateT sPrintIncAccum 10
+-- Hi: 10
+-- ("10",11)
+-- Prelude> mapM (runStateT sPrintIncAccum) [1..5]
+-- Hi: 1
+-- Hi: 2
+-- Hi: 3
+-- Hi: 4
+-- Hi: 5
+-- [("1",2),("2",3),("3",4),("4",5),("5",6)]