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copied!<p>In general, you should try using immutable data types and avoid imperative constructs such as global variables and imperative loops - although using them in F# is fine in many cases, they should be used only when there is a good reason for doing so. Here are a couple of examples where you could use functional approach:</p> <hr> <p>First of all, to make the code more functional, you should avoid using global mutable cache. Instead, your <code>RefreshCache</code> function should return the data as the result (preferably using some functional data structure, such as F# <code>Map</code> type):</p> <pre><code>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 </code></pre> <p>The code that uses it would be changed like this:</p> <pre><code>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 </code></pre> <hr> <p>In the <code>EstablishConnection</code> function, you definitely don't need to declare a mutable variable <code>sr</code>, because in case of an exception, the function will return <code>null</code>. I would instead use <code>option</code> type to make sure that this case is handled:</p> <pre><code>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 </code></pre> <p>The main loop can be written using a recursive function that stops when <code>EstablishConnection</code> fails:</p> <pre><code>let rec loop() = match EstablishConnection() with | Some(conn) -> printfn "[F#] Ready to Receive data" // rest of the code loop() // continue looping | _ -> () // Quit </code></pre>

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