Re: perhaps

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