+// Example Reading String input

+// Example reading input that needs to be coereced back into a primitive

+    System.Console.ReadLine()

+

+let rec promptUser (inputMethod:unit->string) (message:string) (matchingExpression:string->string option) =

+    let formattedMessage = Printf.TextWriterFormat<unit>(message)

+    printfn formattedMessage

+    let input = inputMethod()

+       

+    let result = matchingExpression input

+    match result with

+        | Some x -> x

+        | None -> promptUser inputMethod message matchingExpression

+        

+// Example Usages

+

+let sentenceMatchingExpression (input:string) =

+    if input.StartsWith "A" then Some input

+    else None

+    

+let prompt = "Please enter a string that starts with A."

+

+let result = promptUser getKeyboardInput prompt sentenceMatchingExpression

+

+printfn "You entered %s" result

+

+

+let validNumberOfHoursToWork (input:string) =

+    match System.Int32.TryParse(input) with

+        | (true,int) -> if int <= 40 && int >= 1 then Some input

+                        else None

+        | _ -> None

+        

+let numHoursWorkedPrompt = "Please enter then number of hours worked."

+

+let numHoursWorked = (promptUser getKeyBoardInput numHoursWorkedPrompt validNumberOfHoursToWork) |> Int32.Parse

+