Are you looking out for a simple F# program that reads the input from the Console Window and writes it back ? . Here’s a simple program to demonstrate it.
// AbundantCode F# Tutorials and Code snippets
open System
[<EntryPoint>]
let main argv =
Console.Write("This is Abundantcode's First F# Program")
let inputtext = Console.ReadLine()
// Printing the entered input
Console.Write("You entered:" + inputtext)
0 // return an integer exit code