Functional programming patterns in java.

Reference: https://www.youtube.com/watch?v=YnzisJh-ZNI
Reference: https://www.youtube.com/watch?v=e4MT_OguDKg&index=146
Reference: https://www.amazon.com/Modern-Java-Action-functional-programming/dp/1617293563

This repo is a mix of functional design patterns that we have seen in books or on the internet.

1. try to design you API in a composable way (package: composable)

   class ShoppingAPI {
       static Function<List<Item>, Cart> buy() {
           return Cart::new;
       }
   
       static Function<Cart, Order> order() {
           return Order::new;
       }
   
       static Function<Order, Delivery> deliver() {
           return Delivery::new;
       }
   
       static Function<List<Item>, Delivery> oneClickBuy() {
           return buy()
                   .andThen(order())
                   .andThen(deliver());
       }
   }
   

   • other used classes are as simple as they can be:

     @Value
     class Cart {
         ImmutableList<Item> items;
     
         Cart(List<Item> items) {
             this.items = ImmutableList.copyOf(items);
         }
     }
     
     @Value
     class Delivery {
         Order order;
     }
     
     @Value
     class Item {
         int id;
     }
     
     @Value
     class Order {
         Cart cart;
     }