packages with orphaned instances only

[Henning Thielemann]

Ivan Lazar Miljenovic schrieb:
> On 9 January 2011 07:20, Henning Thielemann
> <lemming at henning-thielemann.de> wrote:
>> If there are multiple equally natural instances, then there should not
>> be one at all.
> 
> It depends what you mean.  In my case, I wanted the String instance
> for Arbitrary to follow certain rules (can't be the textual
> representation of a number, can't have certain characters in it,
> etc.).

This sounds like extra wishes that require a new type or some
preprocessing within a quick check (e.g. filter out digits). You would
not be happy with a private instance for Arbitrary String anyway, since
different tests may have different requirements for the test strings (if
not today, then maybe in future).