Warn if some value is unused

[TysonMN]

There is a bug in F# that prevents this project from turning on warnings for unused values.

  property {
    let! i = Gen.alpha // The value 'i' is reported as unused
    where true
    return i = i
  }

[TysonMN]

Blocked by F# bug https://github.com/dotnet/fsharp/issues/10167

[cmeeren]

I guess you could rename i to _i to work around it.