Validar CUIL

Tests.cs

    [Test]
    public void IsValidatedCUIL_WithValidatedCuil() {
        var returnValue = CUILValidation.ValidateCUIL("20-33817701-2");

        Assert.IsTrue(returnValue.IsOk);
    }

    [Test]
    public void IsValidatedCUIL_WithInvalidatedCuil() {
        var returnValue = CUILValidation.ValidateCUIL("20-33817701-3");

        Assert.IsTrue(returnValue.IsInvalidDigit);
    }

    [Test]
    public void IsInvalidatedString_WithInvalidatedCuil() {
        var returnValue = CUILValidation.ValidateCUIL("20338177013");
        Assert.IsTrue(returnValue.IsInvalidFormat);
    }

ValidarCUIL.fs

// original: https://dl.dropbox.com/u/14102783/Program.fs
// https://twitter.com/AugustoPedraza/statuses/210514248768557056

module CUILValidation

open System
open System.Text.RegularExpressions

let getCheckDigit =
    let validateDigits = [5;4;3;2;7;6;5;4;3;2]
    fun cuil -> 
        match 11 - Seq.sum (Seq.map2 (*) validateDigits cuil) % 11 with
        | 11 -> 0
        | 10 -> 9
        | x -> x

let inline charToInt c = int c - 48

type CUILResult = Ok | InvalidFormat | InvalidDigit

let ValidateCUIL (cuil : string) =
    if Regex.IsMatch(cuil, @"^\d{2}-\d{8}-\d{1}$") then
        let digits = Regex.Replace(cuil, "-", "")
        let checkDigit = digits.[..digits.Length-2] |> Seq.map charToInt |> getCheckDigit
        if checkDigit = charToInt cuil.[cuil.Length-1]
            then Ok
            else InvalidDigit
    else InvalidFormat
//
//open System
//
//printfn "%A" (ValidateCUIL("20-33817701-2"))
//printfn "%A" (ValidateCUIL("20-33817701-3"))
//printfn "%A" (ValidateCUIL("33-70991844-9"))
//printfn "%A" (ValidateCUIL("20338177013"))
//printfn "%A" (ValidateCUIL("20338177013"))