===== Higher order functions and functional closures =====

Using: **higher-order functions**, **infix/prefix** notation, **anonymous functions (lambdas)** and **functional closures** to write better code:

<code haskell>
import Data.Char

-- map examples
addOne :: [Integer] -> [Integer]
addOne = map (+1)

remHead = map tail 

toString = map (:[])

fold op acc [] = acc
fold op acc (x:xs) = x `op` (fold op acc xs)

sum = foldr (+) 0 

-- operatia de adunare, prefixata, este (+)

makeLower = foldr ((:).toLower) []

reverse :: [a] -> [a]
reverse = foldl (\acc x -> x:acc) [] 

</code>