Elm lang shopping Cart implementation. Provide a way to add/remove product to/from cart, increment and decrement quantity of product in a cart. Also calculate total quantity and cart subtotal. Cart item stores datetime when the product was added to a cart. This date should be passed to add function as present in the example below.
Please look into examples/Cartapp.elm for the reference.
import Cart exposing (..)
type alias Product = { id : Int, price : Float, title : String }
apple = Product 1 10.0 "Apple"
add apple cart 12345 ==
[{ product = { id = 1, price = 10.0, title = "Apple" }, qty = 1, date_added = 12345 }]
inc apple (add apple cart 12345 ) ==
[{ product = { id = 1, price = 10.0, title = "Apple" }, qty = 2, date_added = 12345 }]
subtotal .price (add apple cart 12345) == 10.0
subtotal .price (inc apple (add apple cart 12345)) == 20.0
You can also find Cart examples in tests/CartTests.elm file.