From 4f048c922563189a1b87ee1df2e17f6fc150259f Mon Sep 17 00:00:00 2001
From: Anastasios Valtinos <anastasios.valtinos@trint.com>
Date: Thu, 6 Oct 2022 14:24:07 +0300
Subject: [PATCH] Checking Instance knowledge

---
 .../MFAM - Practice/monad.hs                  | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 Haskell Excercises & Code/MFAM - Practice/monad.hs

diff --git a/Haskell Excercises & Code/MFAM - Practice/monad.hs b/Haskell Excercises & Code/MFAM - Practice/monad.hs
new file mode 100644
index 0000000..9792b83
--- /dev/null
+++ b/Haskell Excercises & Code/MFAM - Practice/monad.hs	
@@ -0,0 +1,23 @@
+module MonadicStuff where
+
+-- Checking udnerstanding of Monad instance for Maybe
+-- To write Monad. we need to write ApplICATIVE
+-- To write applicative we need Functor
+--import Data.Maybe
+
+instance Functor Maybe where
+    fmap f Nothing  = Nothing
+    fmap f (Just x) = Just (f x)
+
+instance Applicative Maybe where
+    pure x = Just x
+    -- pure id <*> v = v
+    -- pure should not change the underlying values
+    Nothing <*> _ = Nothing
+    _ <*> Nothing = Nothing
+    Just f <*> Just n = Just (f n)
+
+instance Monad Maybe where
+    return = Just
+    Nothing >>= f = Nothing
+    (Just n) >>= f = f n