secondPart_<Higher order functions>

secondPart_<Higher order functions>

1. Currified functions

   • call two parameters

2. ->

   • take and return
   • naturally associative by right

3. infix functions

4. Higher order in your order

   • Functions can take functions as parameters and also return functions

5. Associations and filters

   • predicate
     • function that says if something is true or false
   • map :: (a -> b) -> [a] -> [b] map _ [] = [] map f (x:xs) = f x : map f xs
   • filter :: (a -> Bool) -> [a] -> [a] filter _ [] = [] filter p (x:xs) | p x = x : filter p xs | otherwise = filter p xs

6. Lambdas

   • Lambdas are anonymous functions that are usually used when we need a function only once
   • \
     • (\xs -> length xs > 15)

7. Folds and origami

   • Folds can be used to implement any function that traverses a list, item by item, and then return a value.
     • Whenever you want to go through a list and return a value, there are possibilities of using a fold
   • a fold takes a binary function, an initial value and a list to fold

8. $

   • Basically it is a function of convenience that we use to avoid having to write many parentheses
     • map a list of functions

9. Composition of functions

   • is to perform a composition of functions with the previous function