namratachaudhary · December 15, 2017 12:25 · Dec 15, 2017 · Dec 15, 2017
diff --git a/LinkedList.hs b/LinkedList.hs
@@ -3,11 +3,11 @@ mylist = (Cons 1 (Cons 2 (Cons 3 Nothing)))
 print mylist
 -- This will show errors
 
--- You cannot run a `show` or `eq` on your mylist 
+-- You cannot run a `show` on your mylist 
 -- because you are not deriving them while defining your list in line 1
 -- So your new definition becomes
 
-data List a = Nothing | Cons a (List a) deriving (Show, Eq)
+data List a = Nothing | Cons a (List a) deriving (Show)
 mylist = (Cons 1 (Cons 2 (Cons 3 Nothing)))
 print mylist
 -- Cons 1 (Cons 2 (Cons 3 Nothing))

diff --git a/LinkedList.hs b/LinkedList.hs
@@ -0,0 +1,37 @@
+data List a = Nothing | Cons a (List a)
+mylist = (Cons 1 (Cons 2 (Cons 3 Nothing)))
+print mylist
+-- This will show errors
+
+-- You cannot run a `show` or `eq` on your mylist 
+-- because you are not deriving them while defining your list in line 1
+-- So your new definition becomes
+
+data List a = Nothing | Cons a (List a) deriving (Show, Eq)
+mylist = (Cons 1 (Cons 2 (Cons 3 Nothing)))
+print mylist
+-- Cons 1 (Cons 2 (Cons 3 Nothing))
+
+
+-- Maybe read the arrows tutorial> https://wiki.haskell.org/Arrow_tutorial
+showHead :: List a -> a   
+showHead l = case l of Cons a _ -> a
+
+-- showHead mylist  => 10 (Not Cons 10)
+
+showTail :: List a -> List a
+showTail Nothing = Nothing
+showTail l = case l of Cons _ a -> a
+
+-- showTail mylist => Cons 99 (Cons 11 Nothing)
+
+showLength :: List a -> Int
+showLength Nothing = 0
+showLength xs = 1 + (showLength (showTail xs)) -- I hope this is right :/
+
+-- showLength mylist => 3
+
+-- The evaluations are lazy. If you define the list of infinite length, it will give you head, tail. 
+-- But if you compute length, it will go into stackoverflow. This is concept called - Holding on to the head. 
+-- The program is holding on to the first value and mutating it - infinitely. 
+-- One way to handle it to make your evaluations strict instead of lazy.