FsCheck problem/query

gistfile1.fs

#r "./bin/Debug/FsCheck.dll"
open System
open FsCheck
//ensure fscheck is fully initialised.
Runner.init.Force()

let whiteList = 
    let x = ['a' .. 'z'] @ ['A' .. 'Z']
    Gen.choose (0, x.Length - 1)
    |> Gen.map (fun i -> x.[i])

type SafeString = SafeString of string with
    member x.Get = match x with SafeString r -> r
    override x.ToString() = x.Get

type UriGenerator =
    static member SafeString() =
        Gen.map (fun (chars:char[]) -> String(chars)) (Gen.arrayOf whiteList)
        |> Arb.fromGen
        |> Arb.filter (fun s -> not (String.IsNullOrEmpty s))
        |> Arb.convert SafeString string

Arb.register<UriGenerator>

// works as expected
Gen.sample 10 10 (UriGenerator.SafeString().Generator)
// returns SafeStrings but not using the defined 'safe' generator above
Gen.sample 10 10 (Arb.generate<SafeString>)

When using Arb.generate the strings returned aren't "safe" and appear to use the default string generator.

Bah I found it needed to be Arb.register()

As you were. :)