lab04b: init

lab04/tree.hs

@@ -0,0 +1,36 @@
+--This works, but it is not generic
+data TreeStringInt =
+    EmptyTSI
+  | NodeTSI String Int TreeStringInt TreeStringInt
+  deriving (Show)
+
+findTsi :: String -> TreeStringInt -> Maybe Int
+findTsi _ EmptyTSI = Nothing
+findTsi s (NodeTSI key i left right) =
+  if key == s then
+    Just i
+  else if s < key then
+    findTsi s left
+  else
+    findTsi s right
+
+
+
+--Using type parameters, we can create a BST in a more generic form
+data Tree k v =
+    Empty
+  | Node k v (Tree k v) (Tree k v)
+  deriving (Show)
+
+--findT :: k -> Tree k v -> Maybe v
+findT :: Ord k => k -> Tree k v -> Maybe v
+findT _ Empty = Nothing
+findT s (Node key val left right) =
+  if key == s then
+    Just val
+  else if s < key then
+    findT s left
+  else
+    findT s right
+
+