clean_arch.fs

// F# version of https://twitter.com/gsferreira/status/1516827091127394309/

open System
open System.IO

type PotentialProcessingError = | StringMissing | StringTooShort

let application store = function
    | None -> Error StringMissing
    | Some (str: string) when str.Length < 5 -> Error StringTooShort
    | Some str -> str |> store

let infrastructure text =
    let path = Path.Combine(Path.GetTempPath(), "my-text.txt")
    printfn $"Storing at {path}"
    File.WriteAllText(path, text)
    Ok ()

let console store =
    printfn "What message do you want to store?"
    match Console.ReadLine() with
        | "" -> None
        | str -> Some str
    |> application store
 
console infrastructure
|> printfn "Stored successfully? %A"

Console.ReadKey() |> ignore