Add remaining haskell book exercises

Haskell-book/28/DifferenceList/app/Main.hs

@@ -0,0 +1,46 @@
+module Main where
+
+import Criterion.Main
+import Data.DList
+import qualified Data.Queue as Q
+import qualified Data.Sequence as S
+
+schlemiel :: Int -> [Int]
+schlemiel i = go i []
+    where go 0 xs = xs
+          go n xs = go (n - 1) ([n] ++ xs)
+
+constructDlist :: Int -> [Int]
+constructDlist i = toList $ go i empty
+    where go 0 xs = xs
+          go n xs = go (n - 1) (singleton n `append` xs)
+
+processQueue :: Int -> Q.Queue Int
+processQueue i = clear $ Q.pop $ fill i Q.empty
+    where fill 0 xs = xs
+          fill n xs = fill (n - 1) (Q.push n xs)
+          clear Nothing = Q.empty
+          clear (Just xs) = clear $ Q.pop $ snd xs
+
+processList :: Int -> [Int]
+processList i = go (schlemiel i)
+    where go [] = []
+          go (x:xs) = xs
+
+processSeq :: Int -> S.Seq Int
+processSeq i = go $ S.fromList $ schlemiel i
+    where go xs = if S.null xs then xs else go (S.deleteAt 0 xs)
+
+main :: IO ()
+main = defaultMain
+    [ bench "concat list" $
+      whnf schlemiel 123456
+    , bench "concat dlist" $
+      whnf constructDlist 123456
+    , bench "process queue" $
+      whnf processQueue 12345
+    , bench "process list" $
+      whnf processList 12345
+    , bench "process sequence" $
+      whnf processSeq 12345
+    ]