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Point of Sale

10 line Point of Sale (POS) application takes barcodes from a USB barcode scanner or keyboard adding matching products. Entering an empty string completes the action and gives the total.

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let products = ["5000171002525","Tuna", 0.59M; "54491014", "Coke", 0.33M]
let stream = Seq.initInfinite (fun _ -> printf ">"; System.Console.ReadLine())
let scans = stream |> Seq.takeWhile (fun s -> s.Length > 0)
let items = 
    scans |> Seq.fold (fun items scan ->
        match products |> List.tryFind (fun (code,_,_) -> scan = code) with
        | Some((_,n,p) as product) -> printfn "%s\t@ %A" n p; product::items
        | None -> printfn "Not found"; items
    ) []
items |> List.sumBy (fun (_,_,price) -> price) |> printf "Total %A"
val products : (string * string * decimal) list

Full name: Script.products
val stream : seq<string>

Full name: Script.stream
module Seq

from Microsoft.FSharp.Collections
val initInfinite : initializer:(int -> 'T) -> seq<'T>

Full name: Microsoft.FSharp.Collections.Seq.initInfinite
val printf : format:Printf.TextWriterFormat<'T> -> 'T

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.printf
namespace System
type Console =
  static member BackgroundColor : ConsoleColor with get, set
  static member Beep : unit -> unit + 1 overload
  static member BufferHeight : int with get, set
  static member BufferWidth : int with get, set
  static member CapsLock : bool
  static member Clear : unit -> unit
  static member CursorLeft : int with get, set
  static member CursorSize : int with get, set
  static member CursorTop : int with get, set
  static member CursorVisible : bool with get, set
  ...

Full name: System.Console
System.Console.ReadLine() : string
val scans : seq<string>

Full name: Script.scans
val takeWhile : predicate:('T -> bool) -> source:seq<'T> -> seq<'T>

Full name: Microsoft.FSharp.Collections.Seq.takeWhile
val s : string
property System.String.Length: int
val items : (string * string * decimal) list

Full name: Script.items
val fold : folder:('State -> 'T -> 'State) -> state:'State -> source:seq<'T> -> 'State

Full name: Microsoft.FSharp.Collections.Seq.fold
val items : (string * string * decimal) list
val scan : string
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 tryFind : predicate:('T -> bool) -> list:'T list -> 'T option

Full name: Microsoft.FSharp.Collections.List.tryFind
val code : string
union case Option.Some: Value: 'T -> Option<'T>
val n : string
val p : decimal
val product : string * string * decimal
val printfn : format:Printf.TextWriterFormat<'T> -> 'T

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.printfn
union case Option.None: Option<'T>
val sumBy : projection:('T -> 'U) -> list:'T list -> 'U (requires member ( + ) and member get_Zero)

Full name: Microsoft.FSharp.Collections.List.sumBy
val price : decimal
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More information

Link:http://fssnip.net/9P
Posted:5 years ago
Author:Phillip Trelford
Tags: pos