TipCalculator_v1.fs

open System

//take sale amount and tip %
//compute the tip amount 
//print out both the tip and the total amount of the bill

let tipAmount saleAmount tipPercentage = tipPercentage/100.00 * saleAmount

let totalAmount saleAmount tipPercentage = (tipAmount saleAmount tipPercentage) + saleAmount

let rec procInput (message:string) lines =
 message |> Console.WriteLine
 match Console.ReadLine() |> Double.TryParse with
  | true,num -> if (num > 0.0) then num else procInput "enter a value greater than 0" lines
  | false,num -> procInput message lines 

[<EntryPoint>]
let main argv = 
 
 let saleAmount = procInput "Please enter the sale amount:" ""

 let tipPercentage = procInput "Please enter the tip %:" ""

 let tipAmount = tipAmount saleAmount tipPercentage
 let total = totalAmount saleAmount tipPercentage
 
 printf "tip: $%A" tipAmount
 printf "total: $%A" total
 
 0