Adding Haskell examples (#17)

* Adding binary search example for Haskell

* Adding selection sort example in Haskell

* Adding Haskell examples for chapter 3

* Adding examples for chapter 4

* Adding examples for chapter 5

* Adding git ignore

* Add Haskell example for BFS

06_breadth-first_search/Haskell/01_bfs.hs

@@ -0,0 +1,25 @@
+import qualified Data.HashMap.Strict as Map
+import Control.Applicative
+
+graph = Map.fromList [
+  ("you", ["alice", "bob", "claire"]),
+  ("bob", ["anuj", "peggy"]),
+  ("alice", ["peggy"]),
+  ("claire", ["mangoes", "jonny"]),
+  ("anuj", []),
+  ("peggy", []),
+  ("mangoes", []),
+  ("jonny", [])
+  ]
+
+connections name = Map.lookup name graph
+
+bfs tosearch searched = case tosearch of
+  Just (x: xs)
+    | x == "mangoes" -> Just x
+    | x `elem` searched -> bfs (Just xs) searched
+    | otherwise -> bfs ((++) <$> Just xs <*> (connections x)) (x : searched)
+  _ -> Nothing
+
+main = do
+  putStrLn (show (bfs (Just ["you"]) []))