Starbucks

Simple DSL for describing cups of Starbucks coffee and computing prices (in dollars).

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module Starbucks

type size = Tall | Grande | Venti
type drink = Latte | Cappuccino | Mocha | Americano
type extra = Shot | Syrup

type Cup = { Size:size; Drink:drink; Extras:extra list } with
    static member (+) (cup:Cup,extra:extra) =
        { cup with Extras = extra :: cup.Extras }
    static member Of size drink =
        { Size=size; Drink=drink; Extras=[] }
    
let Price (cup:Cup) =
    let tall, grande, venti = 
        match cup.Drink with
        | Latte      -> 2.69, 3.19, 3.49
        | Cappuccino -> 2.69, 3.19, 3.49
        | Mocha      -> 2.99, 3.49, 3.79
        | Americano  -> 1.89, 2.19, 2.59
    let basePrice =
        match cup.Size with
        | Tall -> tall 
        | Grande -> grande
        | Venti -> venti
    let extras =
        cup.Extras |> List.sumBy (function
            | Shot -> 0.59
            | Syrup -> 0.39
        )
    basePrice + extras

let myCup = Cup.Of Venti Latte + Syrup
let price = Price myCup

module Starbucks

type size =
  | Tall
  | Grande
  | Venti

Full name: Starbucks.size

union case size.Tall: size

union case size.Grande: size

union case size.Venti: size

type drink =
  | Latte
  | Cappuccino
  | Mocha
  | Americano

Full name: Starbucks.drink

union case drink.Latte: drink

union case drink.Cappuccino: drink

union case drink.Mocha: drink

union case drink.Americano: drink

type extra =
| Shot
| Syrup

Full name: Starbucks.extra

union case extra.Shot: extra

union case extra.Syrup: extra

type Cup =
  {Size: size;
   Drink: drink;
   Extras: extra list;}
  static member Of : size:size -> drink:drink -> Cup
  static member ( + ) : cup:Cup * extra:extra -> Cup

Full name: Starbucks.Cup

Cup.Size: size

Cup.Drink: drink

Cup.Extras: extra list

type 'T list = List<'T>

Full name: Microsoft.FSharp.Collections.list<_>

val cup : Cup

Multiple items
val extra : extra

--------------------
type extra =
| Shot
| Syrup

Full name: Starbucks.extra

static member Cup.Of : size:size -> drink:drink -> Cup

Full name: Starbucks.Cup.Of

Multiple items
val size : size

--------------------
type size =
  | Tall
  | Grande
  | Venti

Full name: Starbucks.size

Multiple items
val drink : drink

--------------------
type drink =
  | Latte
  | Cappuccino
  | Mocha
  | Americano

Full name: Starbucks.drink

val Price : cup:Cup -> float

Full name: Starbucks.Price

val tall : float

val grande : float

val venti : float

val basePrice : float

val extras : float

Multiple items
module List

from Microsoft.FSharp.Collections

--------------------
type List<'T> =
  | ( [] )
  | ( :: ) of Head: 'T * Tail: 'T list
  interface IEnumerable
  interface IEnumerable<'T>
  member Head : 'T
  member IsEmpty : bool
  member Item : index:int -> 'T with get
  member Length : int
  member Tail : 'T list
  static member Cons : head:'T * tail:'T list -> 'T list
  static member Empty : 'T list

Full name: Microsoft.FSharp.Collections.List<_>

val sumBy : projection:('T -> 'U) -> list:'T list -> 'U (requires member ( + ) and member get_Zero)

Full name: Microsoft.FSharp.Collections.List.sumBy

val myCup : Cup

Full name: Starbucks.myCup

static member Cup.Of : size:size -> drink:drink -> Cup

val price : float

Full name: Starbucks.price

Raw view Test code New version

More information

Link:	http://fssnip.net/9w
Posted:	13 years ago
Author:	Phillip Trelford
Tags:	dsl