functional programming - How to execute specific functions with input pattern in F# language -


i'm kinda new f# , trying out simple calculator app. take input user, , want specific functions executed per input. right now, whenever take input user, program executes top bottom. want execute specific functions matching input. if input 6 body of scientificfun() should executed. right executes functions. please help, i'm kinda stuck on one! code is

open system  let mutable ok = true while ok     console.writeline("choose operation:\n1.addition\n2.substraction\n3.multiplication\n4.division\n5.modulo\n6.scientific")     let input= console.readline()        let add =          console.writeline("ok, how many numbers?")         let mutable count = int32(console.readline())         let numberarray = array.create count 0.0         in 0 .. numberarray.length - 1             let no = float(console.readline())             array.set numberarray no         array.sum numberarray     let sub x y = x - y      let mul x y = x * y     let div x y = x / y     let mod x y = x % y     let scientificfun() =          printfn("1. exponential")     match input     | "1" -> printfn("the result is: %f") (add)     | "6" -> (scientificfun())     | _-> printfn("choose between 1 , 6")     console.writeline("would use calculator again? y/n")     let ans = console.readline()     if ans = "n"         ok <- false     else console.clear()

you should define add function: let add() = or let add inputnumbers =

otherwise simplified version below executes functions corresponding input number:

open system  [<entrypoint>] let main argv =        // define functions     let hellofun() =         printfn "%a" "hello"      let worldfun() =         printfn "%a" "world"       let mutable cont = true     let run() =   // set while loop         while cont         printfn "%a" "\nchoose operation:\n 1 hellofunc\n 2 worldfunc\n 3 exit"         let input = console.readline()  // input         match input // pattern match on input call correct function         | "1" -> hellofun()         | "2" -> worldfun()         | "3" -> cont <- false;()         | _ -> failwith "unknown input"       run()  // kick-off loop     0

the [<entrypoint>] let main argv = necessary if compile it. otherwise execute run().


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