Lesson samples

Lecture 03/Scratch/Scratch.hs

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+module Scratch where
+
+mapInteger :: (Integer -> Integer) -> [Integer] -> [Integer]
+mapInteger _ [] = []
+mapInteger f (x:xs) = f x : mapInteger f xs
+
+plus1 :: Integer -> Integer
+plus1 x = x + 1
+
+filterInteger :: (Integer -> Bool) -> [Integer] -> [Integer]
+filterInteger _ [] = []
+filterInteger f (x:xs)
+  | f x == True = x : filterInteger f xs
+  | otherwise = filterInteger f xs
+  
+greaterThanTwo :: Integer -> Bool
+greaterThanTwo x = x > 2
+
+data Tree = Leaf Char
+          | Node Tree Int Tree
+  deriving Show
+  
+tree :: Tree
+tree = Node (Leaf 'x') 1 (Node (Leaf 'y') 2 (Leaf 'z'))