F# Parse command line arguments, expected incomplete structured construct at or before this point ; or ;; - f#

Question

I have a basic F# CLI that mimics F# touch command , my program takes a file name , creates the file if it exists or updates access time if it doesn't.
Core functionality is done, but it is supposed to mimic Linux' command Touch in terms of syntax. The syntax should be 'touch file1.text' for file creation or 'touch --version' for a message I want to print when option is given.
My core problems are:-
1. Having my code follow Linux' syntax -
Current - >>>Test.text = File created.
Expected - >>> touch test.txt or
touch --version = File created or touch command information printed.
Taking --version and --help or similar valid input and printed the corresponding information.
Current result
test.txt // File created
0 //
Expected
touch test.text //file created
0 //
or
Expected
touch --version / touch --help
/* Touch information
Touch information
Touch information
Touch information*/
Tried using the Argu library but seems out of my current scope, currently attempting with argument parser module.
// Learn more about F# at http://fsharp.org
open System
open System.IO
open System.Text
type filename = String
let touch path =
//Console.ReadLine()
if File.Exists path
then File.SetLastWriteTime(path, DateTime.Now)
else
if not(File.Exists path)
then File.WriteAllText(path, " ")
Console.ReadKey()|>ignore
[<EntryPoint>]
let main argv =
printfn "Touch Command - Built using F#"
printfn "Please enter the file you want to touch"
if argv |> Array.contains "Help " then
printfn "Display help here"
exit(0)
printfn "Version information"
exit(0)
for filename in argv do
touch(filename)
0
// return an integer exit code
```
Current result
> test.txt // File created
> 0 // internal
Expected
>touch test.text //file created
>0 //internal
or
Expected
>touch --version / touch --help
>/* Touch information
Touch information
Touch information
Touch information*/
No current errors
When argu library attempted, to many errors to bring to solution board.

Answer 1

argv is an array of strings, so the simplest way to tell if --help or --version is in that array is to use the Array.contains function:
[<EntryPoint>]
let main argv =
printfn "Argv: %A" argv // Helpful in debugging, remove in final version
if argv |> Array.contains "--help" then
printfn "Display help here"
exit(0)
if argv |> Array.contains "--version" then
printfn "Version information"
exit(0)
for filename in argv do
touch(filename)
Note that this example is assuming that you rewrite your touch function to take a filename parameter instead of reading the filename from the console via Console.ReadLine.
Also note that after an attribute like [<EntryPoint>], there's no need to add a second level of indentation. The attribute should be indented at the same level as the let declaration that it's modifying. So you should write your let main argv = line at the top level of your module (i.e., with zero indentation).