Ashley Yakeley ashley at
Fri Aug 11 18:16:32 EDT 2006

John Meacham wrote:
> does anyone else think this would be useful to provide?
>>module Data.Perhaps where
>>data Perhaps = No | Maybe | Yes
>>        deriving(Eq,Ord,Show,Read,Enum,Bounded)
>>instance Monoid Perhaps ...
> I only ask because it has come up as useful several times in projects I
> work on.

I think "Maybe Bool" is better for this. It already separates out for 
you the notion of certainty vs. uncertainty.

What Monoid did you have in mind for it?

Ashley Yakeley

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