Added comments to Ch05

Ch05/Code01_tree/Main.hs

@@ -4,6 +4,7 @@ data Tree a = Node { value :: a
             | Leaf 
             deriving Show
 
+-- Creating a binary tree
 main = do
   let n1 = Node { value = 1, left = Leaf, right = Leaf }
   let n2 = Node { value = 2, left = Leaf, right = Leaf }

Ch05/Code02_rose/Main.hs

@@ -1,7 +1,8 @@
 data Tree a = Node { value    :: a 
                    , children :: [Tree a] }
             deriving Show
-                     
+
+-- Creating a rose tree                     
 main = do
   let n1 = Node { value = 1, children = [] }
   let n2 = Node { value = 2, children = [] }

Ch05/Code03_depth/Main.hs

@@ -1,6 +1,7 @@
 import Data.Tree (rootLabel, subForest, Tree(..))
 import Data.List (tails)
 
+-- Traversing a tree depth-first
 main = do
   print $ depthFirst someTree
   print $ add someTree

Ch05/Code04_breadth/Main.hs

@@ -1,6 +1,7 @@
 import Data.Tree
 import Data.List (tails)
 
+-- Traversing a tree breadth-first
 main = do
   print $ breadthFirst someTree
   print $ add someTree

Ch05/Code05_fold/Main.hs

@@ -7,6 +7,7 @@ data Tree a = Node { value    :: a
             | Null
             deriving Show
 
+-- Folding through a tree
 main :: IO ()
 main = print $ add someTree
 

Ch05/Code06_height/Main.hs

@@ -1,6 +1,7 @@
 import Data.List (maximum)
 import Data.Tree
 
+-- Computing the height of a tree
 main = do
   print $ height someTree
 

Ch05/Code07_bst/Main.hs

@@ -1,5 +1,6 @@
 import BSTree
 
+-- Using a binary search tree
 main = do
   let tree = single 5
   let nodes = [6,4,8,2,9]

Ch05/Code08_valid/Main.hs

@@ -15,6 +15,7 @@ someTree = root
         n3   = Node 3 Null Null
         n4   = Node 4 Null Null
 
+-- Verifying a binary search tree
 valid :: Ord t => Tree t -> Bool
 valid (Node v l r) = leftValid && rightValid
   where leftValid  = if notNull l then valid l && value l <= v else True

Ch05/Code09_avl/Main.hs

@@ -1,9 +1,10 @@
 import Data.Tree.AVL
 import Data.COrdering
 
+-- Using an AVL balanced binary tree
 main = do
   let avl  = asTree fstCC [4,2,1,5,3,6]
   let min  = tryReadL avl
   let max  = tryReadR avl
   print min
-  print max
+  print max

Ch05/Code10_heap/Main.hs

@@ -1,9 +1,10 @@
 import MinHeap
 
+-- Using a min-heap
 main = do
   let heap = foldr (\x -> insert x x) empty [11, 5, 3, 4, 8]
   print $ weights heap
   print $ weights $ iterate deleteMin heap !! 1
   print $ weights $ iterate deleteMin heap !! 2
   print $ weights $ iterate deleteMin heap !! 3
-  print $ weights $ iterate deleteMin heap !! 4
+  print $ weights $ iterate deleteMin heap !! 4

Ch05/Code11_huff/Main.hs

@@ -7,6 +7,7 @@ import Data.Map (fromList, (!))
 
 freq xs = map (\x -> (head x, length x)) . group . sort $ xs
 
+-- Encoding a string using Huffman codes
 main = do
   rsp <- simpleHTTP (getRequest "http://norvig.com/big.txt")
   html <- fmap (takeWhile isAscii) (getResponseBody rsp)

Ch05/Code12_huff/Main.hs

@@ -7,6 +7,7 @@ import Data.Map (fromList, (!))
 
 freq xs = map (\x -> (head x, length x)) . group . sort $ xs
 
+-- Decoding a Huffman code
 main = do
   rsp <- simpleHTTP (getRequest "http://norvig.com/big.txt")
   html <- fmap (takeWhile isAscii) (getResponseBody rsp)