My first F # program

Question

I just finished writing my first F # program. Functionality wise code works the way I wanted, but not sure if the code is efficient. I would really appreciate if anyone could look at the code for me and point out areas where the code could be improved.

Thanks Sudaly

open System
open System.IO
open System.IO.Pipes
open System.Text
open System.Collections.Generic
open System.Runtime.Serialization


[<DataContract>] 
type Quote = { 
    [<field: DataMember(Name="securityIdentifier") >] 
    RicCode:string
    [<field: DataMember(Name="madeOn") >] 
    MadeOn:DateTime
    [<field: DataMember(Name="closePrice") >] 
    Price:float 
    }

let m_cache = new Dictionary<string, Quote>() 

let ParseQuoteString (quoteString:string) = 
    let data = Encoding.Unicode.GetBytes(quoteString)
    let stream = new MemoryStream() 
    stream.Write(data, 0, data.Length); 
    stream.Position <- 0L 
    let ser = Json.DataContractJsonSerializer(typeof<Quote array>) 
    let results:Quote array = ser.ReadObject(stream) :?> Quote array
    results

let RefreshCache quoteList =
    m_cache.Clear()
    quoteList |> Array.iter(fun result->m_cache.Add(result.RicCode, result))


let EstablishConnection() =
    let pipeServer = new NamedPipeServerStream("testpipe", PipeDirection.InOut, 4)
    let mutable sr = null
    printfn "[F#] NamedPipeServerStream thread created, Wait for a client to connect"
    pipeServer.WaitForConnection()
    printfn "[F#] Client connected."
    try
        // Stream for the request. 
        sr <- new StreamReader(pipeServer)
    with
    | _ as e -> printfn "[F#]ERROR: %s" e.Message
    sr


while true do
    let sr = EstablishConnection()
    // Read request from the stream.
    printfn "[F#] Ready to Receive data"

    sr.ReadLine()  
    |>  ParseQuoteString  
    |>  RefreshCache

    printfn "[F#]Quot Size, %d" m_cache.Count
    let quot = m_cache.["MSFT.OQ"]
    printfn "[F#]RIC: %s" quot.RicCode
    printfn "[F#]MadeOn: %s" (String.Format("{0:T}",quot.MadeOn))
    printfn "[F#]Price: %f" quot.Price

Answer 1

In general, you should try to use immutable data types and avoid real constructs such as global variables and imperative loops, although using them in F # is great in many cases, they should only be used when there is a good reason for this. Here are some examples where you can use a functional approach:

---

, , . RefreshCache ( , ​​ F # Map):

let PopulateCache quoteList = 
  quoteList 
  // Generate a sequence of tuples containing key and value 
  |> Seq.map (fun result -> result.RicCode, result)
  // Turn the sequence into an F# immutable map (replacement for hashtable)
  |> Map.ofSeq

:

let cache = 
  sr.ReadLine()   
  |>  ParseQuoteString   
  |>  PopulateCache

printfn "[F#]Quot Size, %d" m_cache.Count 
let quot = m_cache.["MSFT.OQ"] 
// The rest of the sample stays the same

---

EstablishConnection sr, null. option, , :

let EstablishConnection() = 
    let pipeServer = 
      new NamedPipeServerStream("testpipe", PipeDirection.InOut, 4) 
    printfn "[F#] NamedPipeServerStream thread created..." 
    pipeServer.WaitForConnection() 
    printfn "[F#] Client connected." 
    try // Wrap the result in 'Some' to denote success
        Some(new StreamReader(pipeServer))
    with e -> 
        printfn "[F#]ERROR: %s" e.Message 
        // Return 'None' to denote a failure
        None 

, , EstablishConnection :

let rec loop() =
  match EstablishConnection() with
  | Some(conn) ->
      printfn "[F#] Ready to Receive data"
      // rest of the code
      loop() // continue looping
  | _ -> () // Quit

Answer 2

...

, "use", "let" , , IDisposable.

EstablishConnection while ( ), , , .

Answer 3

, , , , ( I/O). , #.

-, , , , .